How the 49ers defense has changed since the last time they played the Chiefs

I’ve seen writers covering the Kansas City Chiefs referencing the last time they played the San Francisco 49ers as evidence to why the Chiefs will win Super Bowl LIV. Example:

That writer has also reference the 2019 preseason matchup between the two teams as well. That’s led to fans regurgitating his info:

Believe it or not, the 49ers will look different on defense almost a year and a half later. In Week 3 of 2018, San Francisco had two sacks. One of them came from Antone Exum Jr. They missed 17 tackles that game. Six of those were by Reuben Foster, who was also picked on in coverage. Foster allowed eight receptions on ten targets for a total of 92 yards. Malcolm Smith was also a victim of a few passes. Neither of those players will see the on Super Bowl Sunday.

This isn’t to attack Seth or anyone else referencing that game. There are parts of that game—particularly the success Kansas City had against San Francisco’s defense in the screen game—that Andy Reid and company will likely use.

Differences on defense

During the final three games of the regular season, Fred Warner gave up a combined 96 yards in coverage. San Francisco’s defense doesn’t give up much of anything over the middle of the field, particularly the shorter parts of the field. They are second in the NFL in DVOA at defending short passes. Why? Well, the trio of linebackers isn’t falling for play fakes, and each can flat out fly. So, in the event they are fooled, they make that up with their speed. The athleticism the 49ers have at the second level will go a long way in their ability to get the Chiefs off the field Sunday.

The pass rush, of course. The 49ers had two sacks the last time these two teams played. PFF credited the defense with 21 total pressures. DeForest Buckner led the way with six, while Cassius Marsh was the runner up with four. No other player had more than two. Replace Marsh with Nick freaking Bosa and Dee Ford. Add in the best version of Arik Armstead, and you have yourself the best defensive line by a good margin in football. During the first eight games when Ford was healthy, the fewest pressures the 49ers had was 17, and that came when the team scored 51 points against the Carolina Panthers. From a pressure standpoint, this team is night and day from a season ago. The same cannot be said for the Chiefs offensive line. When you watch them, the center and right guard feel like weak links, while the left side of the line struggled with stunts.

Coverage changes

Pass game coordinator Joe Woods may have been the most critical addition from a scheming standpoint to this defense. This season, the 49ers secondary is rarely out of position, or in a situation where a receiver isn’t accounted for. Gone are the days where you can line up in a 3x1 set and attack this “Cover-3” defense. This is how most 3x1 sets against the Niners look, and why I keep harping on the importance of speed:

That’s man coverage across the board on 3rd & 9. There’s nowhere to throw the ball.

This next play against the Saints is the biggest schematic change. The 49ers are no longer “spot dropping” in zone coverage. Instead, every defender is relating to a specific receiver, hence, “zone match.”

Every “over” route or intermediate crossing route is now accounted for, and that’s why San Francisco is at the top of the league in DVOA for short/intermediate passes. Add in the pass rush, and that’s why the Vikings and Packers have scored on five of 21 possessions in the playoffs.

What’s different? The health, the speed, the experience, and, most importantly, the confidence. San Francisco has played at a high level for four months. Even the “down” part of the season in December, the 49ers had a top-10 passing defense. They were that good earlier in the season that it seemed like the defense was struggling. A healthy 49ers defense has an identity and we haven’t seen an offense crack the code yet. Add in 11 sure tacklers that are flying to the ball like their life depends on it, and you have the one defense in the league that’s equipped to stop a healthy Chiefs offense.