Part of the scuttlebutt during the lead up to this week's 49ers-Rams game has centered on the availability of each team's starting running back. Frank Gore is probable with a neck strain, while Steven Jackson is out with a thigh strain. The conventional wisdom has been that, while the Rams are a horrible team this season, they essentially have "NO CHANCE, NO CHANCE" (ala Joe Starkey) when Jackson isn't playing. On the surface, it seems that the conventional wisdom is right. The Rams have lost by a combined score of 104-32 in the 3 games since Jackson's injury, and have only rushed for 71.3 yards per game without him. It also doesn't help that, in the two weeks prior to Jackson's injury, the Rams registered their only 2 wins of the season. On the flip side, Gore starting all 9 games hasn't seemed to have much of a positive impact on the 49ers' win-loss record. Jackson must be more valuable to the Rams than Gore is to the 49ers, right? Well, like most things in this era of the NFL, you can basically throw conventional wisdom out the window. And when the conventional wisdom is based on game stats provided by the NFL, there's likely to be a garbage can outside that window. So here's the question I'll address in this week's statistical preview: Is Steven Jackson more valuable to the Rams than Frank Gore is to the 49ers?

Football Outsiders has a statistic called Defense-Adjusted Yards above Replacement (DYAR) that basically tells you what a player's value is to his team. As the name implies, a player's DYAR is defined as the amount of yardage a player has gained for his team above and beyond what the team would gain if they replaced him with an average substitution at his position. For example, the most valuable running back right now, Clinton Portis, has a DYAR equal to 268, which means that, if the Redskins had Joe the Replacement at running back this season instead of Portis, they would have 268 fewer offensive yards. Another way of looking at DYAR is that, were Portis to get hurt and miss a game for the Redskins, they could expect to gain about 30 fewer yards on offense (268 yards divided by 9 games) with Joe The Replacement at running back.

After the jump, I'll answer the value question by comparing DYAR stats for Jackson and Gore, identify five crucial game situations to watch for during the Rams game, and make my game prediction...

AN INCONVENIENT TRUTH

Here are the DYAR stats for Jackson and Gore:

As you can see, it's not even a contest here. Frank Gore is the 5^th-most valuable running back in the league, with his absence in favor of Joe the Replacement meaning about 15 fewer yards of offense for the 49ers. In contrast, Steven Jackson is one of the 10 least valuable starting running backs in the NFL. Putting it in even more starkly (ala Joe the Starkey?), Steven Jackson is only about 2 yards better per game than Joe the Replacement!!!

Football Outsiders has another statistic called Effective Yards (EYds) that translates the now-familiar DVOA into rushing yards by taking into account a player's yards per attempt in specific game situations (e.g., 2^nd and long). While DYAR tells you how valuable a running back is overall, EYds tells you how valuable he is given the game situations in which he's actually run the ball. You can compare EYds to the running back's actual rushing yardage total to see whether his actual rushing yards are legit or if they're the artificial result of running the ball in favorable game situations (e.g., a draw on 3^rd and long). For example, Clinton Portis has an EYds equal to 1,125, while his actual rushing yardage total is 995. This means that Portis has been running the ball extremely well in situations where most other running backs do not. Another way to look at it is that, if Portis's 200 rushing attempts were not in such tough situations, his yards per attempt would be 5.6 (1,125 divided by 200), which is over half a yard higher than the 5.0 yards he's actually gained per attempt this season.

Here are the rushing yardage stats for Jackson and Gore (yards per attempt is in parentheses):

As was the case with the DYAR comparison, there is no comparison when it comes to EYds. Gore has gained over half-a-yard more per rushing attempt than Jackson this season (4.6 vs. 4.1) despite those attempts being in game situations that are more difficult for the average running back. Even more to the point, if Jackson had been running the ball for the Niners this year, he'd have gained over one yard less per attempt than Gore has (3.9 vs. 5.0). So on 3^rd and 4 for the 49ers, let's say, Gore would get the first down while Jackson would not.

Bottom line: Based on their DYAR and EYds-stats that aren't skewed by differences between the caliber of defenses they've faced or the game situations in which they've run the ball-Gore is waaaaaaaaaaay more valuable to the 49ers than Jackson is to the Rams. In terms of this week's game, the impact of losing Jackson for the Rams is nothing compared to what the impact would be if the two-headed monster of Michael Robsinson and DeShaun Foster were running the ball for our beloved San Francisco 49ers.

49ERS-RAMS DVOA MATCHUP

Here's how the 49ers stack up against the Rams in terms of DVOA:

As bad as the Niners suck this season, the Rams are in an entirely different galaxy of suckitude. To put the Rams' total DVOA into perspective, the 2-14 Niners of 2004 had a total DVOA of -45.0%, and the 4-12 Niners of 2005 had a total DVOA of -54.5%. In fact, up until a few weeks ago, Football Outsiders actually had a "worst DVOA ever" watch going on regarding the 2008 St. Louis Rams. Needless to say, then, this is a very winnable game for the 49ers. They're 33.8% more efficient overall than the unfathomably bad Rams, which is almost identical to the advantage they had against the Lions. That certainly bodes well given the result. In terms of the three team units, the 2^nd-ranked 49ers special teams (thank you Allen Rossum) has about a 5% advantage over the Rams' special teams, while the Niners gain most of their DVOA advantage when the Rams offense is on the field (+23.7%). Finally, when the 49ers offense is on the field, we should expect them to only perform about 8% better than an average NFL team would against the Rams defense. Keep in mind, however, that most of the 49ers' truly-offensive offensive stats were "achieved" back in the JT O'Mulligan era.

THE DEVIL IS IN THE DETAILS

Below are the five SVW's to focus on during this week's 49ers-Rams matchup:

Unlike the Cardinals matchup, the 49ers have a few game situations that they can exploit against the Rams. Essentially, what these SVWs suggest is that we better be seeing a heavy dose of Frank Gore this week, especially on 2^nd down. Finally!!! Mike Martz's signature pass-on-first, run-on-second, pass-on-third play-calling philosophy might actually pay off! Wait...that 3^rd down pass might not work so well given the Rams' #7 3^rd-down pass defense. Oh well.

"WITH HIGH HOPE FOR THE FUTURE, NO PREDICTION IS VENTURED." - ABRAHAM LINCOLN

Given the statistical matchup between the 49ers and the Rams, and taking into account that Steven Jackson's absence means practically nothing for the Rams' offense, here's my prediction for this week's game:

**DVOA, DYAR, and EYds statistics used to produce this article were obtained from Football Outsiders.