Arik Armstead (8 games): B-
Armstead has had a tough time in his career as a 49er. Arguably over-drafted, it nevertheless made some sense given Armstead’s physical tools. With the likes of Justin Smith, Tank Carradine, Quinton Dial and Darnell Dockett all still on the roster, Armstead could develop behind them. As it was, Smith retired soon after the draft and Dockett never played a regular season game, forcing Armstead into the lineup earlier than expected. When considering that and the various schematic and positional changes Armstead has been forced to endure, it is hardly surprising he hasn’t developed quite the way fans might have hoped. Nevertheless, he’s demonstrated some real quality this season, notably against the run where he frequently is far too much for offensive linemen to handle. He has contributed as a pass rusher, but he isn’t anywhere near as disruptive on a down to down basis as a pass rusher as his physical tools suggest he could be.
DeForest Buckner (8 games): B+
Buckner hasn’t been quite as disruptive as he was last season, perhaps because he has been moved around the defensive line more to accommodate the likes of Solomon Thomas, Arik Armstead and Sheldon Day on passing downs. He’s also been asked to rush as part of a wider plan, which has seen him stunting more to create openings for other players, compared to being the centre (only?) piece of the 49ers pass rush plan last season. The commitment by the 49ers to rushing as more of a unit has nevertheless rewarded Buckner - he has more sacks at the halfway mark this year then he did for the whole of last season. Still a freak of nature whose size, power, athleticism and technique give most offensive linemen absolute fits, Buckner is the key piece on the 49ers’ defensive line whose presence draws attention away from the 49ers’ other pass rushers. His pass rush plan could use some more variation, but Buckner remains an extremely high calibre interior linemen.
Earl Mitchell (8 games): C
Mitchell is having a better season this year than last, and he regularly shows his stoutness against the run as well as a real motor to get out in pursuit of plays after they seemingly pass him by. He has very little value as a pass rusher - something that has led to some calls to see his time drastically reduced in favor of pairing Buckner and Solomon Thomas at the defensive tackle spots - but his value as a space eater who can take on double teams at the point of attack is still unmatched on this team.
Solomon Thomas (8 games): C+
That Thomas is still better as a run stopper than a pass rusher is no bad thing in itself, but his continued lack of impact as a pass rusher is certainly worrying. The burst and power that makes him so effective as a run stopper, wherever he is used along the defensive line, are simply not translating to any kind of pass rushing prowess. It’s also not quite as simple as kicking him inside - Thomas inside vs Thomas outside isn't some sort of Jekyll and Hyde act. He is certainly better as an inside rusher - he seems to hold the athletic edge over many interior offensive linemen in the NFL, but this hasn’t made him sufficiently more effective getting to the quarterback. He still seems to be unable to put together a clear pass rushing plan, but I do believe he needs to be given more time as an inside pass rusher as the season moves on. His lack of usage there so far might, unfortunately, be recognition from the coaches that the 49ers have several better pass rushing options.
Ronald Blair III (8 games): B-
Blair has well and truly forced his way into the rotation at defensive end with some impressive showings in the first half of 2018. He’s shown greater all round ability than Solomon Thomas, producing as both a run defender and pass rusher; giving the 49ers’ significant flexibility with their defensive line rotations. Despite testing nowhere near as well as Thomas, Blair appears a better athlete at this point, notably when rushing the passer, where he also appears more polished. His sacks and pressures haven’t generally been extraordinary explosive efforts, but the product of technique and playing until the whistle. Coming up big in some key moments, Blair’s place in the defensive end rotation should be secure.
Cassius Marsh (8 games): C-
Marsh’s real value to the 49ers appears to come with his versatility. He’s not a particularly effective pass rusher, normally requiring a stunt or the (rare) get off based explosion around the edge. Despite this, he is often on the field, where he is effective enough against the run to see snaps outside of obvious passing situations and good enough in coverage to hold up in either man to man or zone when Robert Saleh dials up some creative blitzes to engineer pressure. Despite this, Kyle Shanahan’s offseason comments that the jilted draftee edge rushers would have had to be ‘pretty good’ to beat out Marsh do seem somewhat questionable given what the primary strength of edge rushers needs to be.
Sheldon Day (8 games): B-
Day has played his way into a crucial role in the defensive line rotation, where he is capable of taking snaps as either the 3-technique or the nose tackle. Stout enough vs the run, Day’s real impact comes as a pass rusher where his low centre of gravity and explosiveness off the snap allows him to get into and beyond offensive linemen quickly. This ability has ensured he continues to beat out promising second year player D.J. Jones as the third and final defensive tackle to dress on game day.
D.J. Jones (4 games): C
Jones hasn’t had a huge amount of opportunity this season, primarily because he isn’t a good enough pass rusher to really be an option to spell DeForest Buckner. He would probably be a more well used piece if the 49ers had more edge rushing talent (that’s a debate for another day), because his ability vs the run is extremely impressive. Not quite as stout against double teams as Mitchell, Jones is arguably more capable than his more experienced counterpart on the move, where his lateral mobility and overall movement skills really stand out.
Malcolm Smith (6 games): C
Once he finally saw the field as a 49er, Smith has gone about his work with reasonable effectiveness but has largely been a nondescript member of the defense. Asked to play the SAM role in a different way than Eli Harold was last season, Smith has been acceptable in coverage (his athleticism and mobility is clearly superior to Harold’s) and his run defense has also been reasonable. He doesn’t look like he should have the size to take on tackles and tight ends, but Smith is a savvy player with a good understanding of his job from play to play, ensuring he manages to get the job done a decent amount of the time.
Fred Warner (8 games): B+
Warner has been given some serious responsibility as the quarterback of the defense in just his first year and he’s performed well. The 49ers’ alignment issues in part stem from the inexperience at MIKE linebacker and free safety; Warner himself has found himself in the wrong gap a few times. More experienced players at those spots recognize those issues more quickly and correct them before the snap. It’s also clear his communication with the players around him is still in a developmental stage. None of these things are a surprise however. Warner’s speed around the field shows up every game, and barring the LA Rams game where their pre-snap motion clearly overwhelmed both Warner and Foster (both were frequently the last players to move and were no longer trusting their eyes), his decisiveness has paired nicely with his athleticism to produce some splash plays. Rookie linebackers aren't normally as well rounded as Warner has been - his future looks extremely positive.
Reuben Foster (6 games): (Incomplete)
The reason for this grade exception is that we can clearly see Foster is injured and playing nowhere near the level he can do. Shoulders are a valuable part of a collision sportsman’s anatomy, especially one such as Foster who’s required to take on blocks, get hands on players in coverage and make tackles. Playing with essentially one shoulder, Foster has been a shadow of the player he was. The physical effects of the shoulder injury are clear, but the mental effects are also somewhat apparent with Foster at times hesitating before coming downhill and initiating contact. At times, you can probably question his processing speed — much like Warner, Foster was truly befuddled by the LA Rams’ offense at times but he has been slower to recognize plays developing than Warner. Also affected by the communication mishaps with his linebacking partner, this season looks set to be a lost one for Foster. At this stage, it’s unclear why the 49ers continue to throw him out there and risk causing further, possible long term damage to his shoulder.
Mark Nzeocha (4 games): D
Nzeocha started the season at SAM linebacker because Malcolm Smith was hurt, and ultimately failed to retain the job because of his tackling. His coverage was alright and he did a decent enough job taking on blockers, but his tackling was for the most part absolutely woeful. Perhaps he is the unlucky poster boy of the 49ers’ tackling woes, but tackling that badly at linebacker is clearly going to be a major issue. If Foster were to be shut down, we could potentially see Nzeocha back in the side if the team favored moving Malcolm Smith to WILL linebacker instead of Elijah Lee. Nzeocha’s tackling has to have improved.
Elijah Lee (4 games): C+
The aforementioned possibility of moving Smith to WILL linebacker to get Mark Nzeocha back into the lineup should not be the avenue the team follow should they shut down Reuben Foster. Lee has been quite capable when he’s been on the field, showing NFL calibre physicality and athleticism. He hasn’t been tested enormously when he was on the field, but he has shown enough to suggest he can hold up effectively in relief of Foster or indeed Fred Warner, should anything happen to the rookie (please no).
Richard Sherman (6 games): B+
Sherman has been having an impressive return from his achilles injury, even though his repeated calf and ankle injuries suggest he is by no means all the way back. It is worth asking the extent to which he has benefited from the dysfunction at the opposite cornerback spot; offenses have had little need to throw the ball his way. Invariably in good coverage, and clearly still a master of this scheme, it was still somewhat disconcerting to see him successfully targeted during the Cardinals’ game winning drive - those were the sort of occasions that he previously relished and normally came out on top in. He is still largely infallible when able to get his hands on receivers at the LOS.
Ahkello Witherspoon (7 games): C
Giving Witherspoon an average grade might be a little controversial. Nevertheless, his two worst games were when he was carrying a lower body injury and in the past two weeks, many of his reps have been extremely impressive. The main issue has been the communication between Witherspoon and his fellow defensive backs, with multiple examples of them being on different pages. That’s something that needs to improve moving forwards. Witherspoon can struggle on deep outs, comebacks and curls, but that’s not particularly surprising for a tall defensive back attempting to play the technique the 49ers teach their cornerbacks. The past two weeks, we’ve seen the Witherspoon we expected to see in his second season - showing the patience at the LOS to force receivers to work laterally, getting his hands on them and running their routes for them. How he plays through the second half of the season will go a long way towards shaping the 49ers’ plans at the cornerback position. Will they continue to develop Tarvarius Moore to eventually play opposite Witherspoon, or will they go and grab someone who can start opposite Richard Sherman?
Greg Mabin (4 games): D
Mabin has just been released by the 49ers, but I think he’s likely to be re-signed to either the practice squad or the 53 man roster if the 49ers can solve their injury problems at the SS position. Mabin was far less likely to be claimed by another team than rookie Tarvarius Moore, so was the only defensive back the team could really release to make room for Marcell Harris following the injuries to Antone Exum and Jaquiski Tartt. Mabin had been playing reasonably well, albeit with the seemingly compulsory defensive back communication breakdowns, before his meltdown against Green Bay. The 49ers talk about overcoming coaching - Mabin shouldn’t have needed to be told to protect the sidelines as the Packers sought to drive downfield. His athleticism may well prevent him from developing into a high calibre corner, but his physicality and technique mean he has potential to improve and be at least a serviceable starter should the 49ers bring him back.
K’Waun Williams (8 games): B-
Williams’ value to the 49ers cannot be understated given the importance of the nickel corner position in the modern NFL. An excellent coverage player, able to play man or zone coverage at a high level, Williams also has the requisite physicality to get heavily involved in the 49ers rush defense as well as contribute as a blitzer - crucial to Robert Saleh’s creative blitzes. He hasn’t been quite as effective against the run this season, seemingly missing a few more tackles, but he’s still an extremely capable slot cornerback.
Jaquiski Tartt (6 games): B+
With the inexperience around him at free safety and linebacker, Tartt has had a huge amount of responsibility trying to make up for that. He has been a force against the run, consistently in attack mode which has resulted in a number of defensive stops. His coverage ability has remained impressive; he could and arguably should have had two pick sixes in just six games. Pair that with his interception against Arizona where he read the play developing perfectly and a near miss against Detroit (where Matt Stafford somehow squeezed a ball over him), Tartt could have had four interceptions in 6 games. That’s a sign that he's invariably in the right spot and that his turnover count will definitely start increasing. The 49ers will hope he can play through his shoulder issues given his importance to this defense.
Adrian Colbert (6 games): D-
Colbert is another who was affected by injury in the early part of the 2018 campaign - it was clear he wasn't moving well out on the field. However, as the season progressed it was also clear that his communication with his teammates wasn’t where it needed to be. It seemed as if the amount he was trying to process at the free safety spot was too much for him, resulting in him missing assignments. At the free safety spot in this defense, that isn't acceptable, though it is somewhat understandable given his inexperience. Now out for the rest of the season, the 49ers and Colbert will hope the game will have slowed down sufficiently in his third season that he won’t be missing assignments in the same way, enabling him to get back to the impressive performances he showed as a rookie.
Jimmie Ward (6 games): C+
For some reason, it seems 49ers’ coaching staffs feel compelled to move Ward around the defense, despite seemingly believing he’s one of their best eleven defenders. Actions speak louder than words in that regard. Nevertheless, Ward somehow finds a way to perform reasonably when out on the field. His move to free safety seemed to create more soundness on the back end, and though he has the same issue as most of the 49ers’ other corners regarding comebacks, deep outs, curls etc, he competed well and was solid contesting throws downfield. He too missed some assignments at corner, but it seems an overall lack of quality communication between the outside corners and the free safety was as responsible for that as individual error. His re-insertion into the FS rotation is an interesting one; does it mean that the 49ers are giving serious thought to allowing Ward another crack at making the position his own, potentially beyond this season? Or is it strange short sightedness in not allowing D.J. Reed to cut his teeth more on the back end? Ward is quite capable of playing the role at a good level - his physicality and tackling invariably stands out - so this will be an interesting storyline to follow as the season moves on.
D.J. Reed (4 games): C+
Reed was supposedly the understudy at free safety to Adrian Colbert, but he was passed over in favor of Jimmie Ward. Given the communication issues that have plagued the 49ers’ defense, it does make some sense to get the more experienced Ward back at free safety to try to resolve or reduce those issues. Nevertheless, in a lost season, why would the 49ers not get Reed back there to gain experience? His performances have generally been fine, despite his tackling leaving something to be desired. He shows a good feel for coverage and is a similar sort of player to Ward when considering his ability to flex between safety, corner and nickel corner. Perhaps the team just want to give him more time to develop, or maybe they have taken the decision to get more experience around Fred Warner and Ahkello Witherspoon. The second half of the season might provide us with more clues.
Takeaways from defensive grades
The big takeaway is clearly the lack of an explosive pass rusher off the edge. Even Ronald Blair, who has 4 sacks so far, isn't the type of explosive pass rusher the 49ers really need off the edge, though he could prove an excellent complementary piece. Furthermore, a lack of experience, notably at the linebacker spots and at free safety, have hurt the soundness of the defense, contributing to the busts that have so infuriated the fans. That same inexperience, as well as injury has certainly contributed to the sophomore slumps of previously impressive rookies Reuben Foster, Ahkello Witherspoon and Adrian Colbert - all of whom have/had key roles on the defense.
Nevertheless, with more senior players such as DeForest Buckner, Blair, Jaquiski Tartt and Richard Sherman performing well, in addition to promising rookie Fred Warner quarterbacking the defense with impressive effectiveness given his own inexperience, there should be some hope that the 49ers defense can improve through the second half of the campaign and carry that over into the following season, where one has to hope a long awaited stud edge rusher or two will appear in red and gold.