Brian Westbrook was once the most important player on the Philadelphia Eagles' offense. At first glance, it looks like the Eagles are losing a huge backfield threat. However, is the loss of Westbrook "addition by subtraction" for the Eagles running game?
I am going to look at the 2009 season and compare the games the Eagles played with Westbrook and the games they played without him. Because Westbrook missed eight games in 2009, we have an evenly split sample of eight games with Westbrook and eight without him.
One statistic that I use is what I like to call "expected stats." The concept is simple: take each opponent's rushing yards per game allowed and sum them together; the result is roughly the amount of rushing yards that the average team would have against that schedule. The same concept applies to rushing attempts, touchdowns, and fumbles. Yards per attempt (YPA) is self-explanatory in this case.
Once I calculated the expected stats, I took the actual stats and compared them to see how much better or worse the Eagles' did than the average opponent. I also took the percentage, which is simply the actual divided by the expected, multiplied by 100.
The strength of this approach is that it allows an adjustment for the fact that the team might be facing tougher rush defenses in one set of eight games or the other, whereas raw stats (rushing yards, touchdowns, etc.) do not make this adjustment.
So, after my calculations, here are the results:
Expected stats: 228.5 attempts, 1,010 yards, 4.42 YPA, 7 TD's, 11.94 fumbles
Actual stats: 167 attempts, 700 yards, 4.19 YPA, 3 TD's, 14 fumbles
Percentage of expected: 73.1 percent attempts, 69.3 percent yards, 94.8 percent YPA, 42.9 percent TD's, 117.3 percent fumbles
Expected stats: 219.8 attempts, 911.38 yards, 4.15 YPA, 7.06 TD's, 12.625 fumbles
Actual stats: 216 attempts, 938 yards, 4.34 YPA, 11 TD's, 9 fumbles
Percentage of expected: 98.3 percent attempts, 102.9 percent yards, 105.6 percent YPA, 155.8 percent TD's, 71.3 percent fumbles
The run defenses that the Eagles played without Westbrook were actually stronger than the run defenses that they played with Westbrook, yet the averages across the board were much better.
There is one big thing to notice about the two though: compare the number of attempts. The yards per attempt for the season was solid, but for whatever reason the Eagles ran the ball more when Westbrook was not playing.
For example, in the loss to Oakland, the Eagles only ran the ball 14 times despite averaging nearly 4.8 yards per carry against a team that was ranked seventh in pass defense but 29th in rush defense. In that type of scenario, the number of attempts needs to be around 30, maybe even higher.
Without Westbrook though, the fewest carries that the Eagles had in any one game was 23, and the Eagles averaged 27 carries a game. As a result, the running game had strong performances in each game, averaging 117.25 yards per game.
One reason for this could be that Andy Reid was using Westbrook as a decoy to open up big passing plays down the field. As a result, the Eagles ran the ball less and also gave fewer carries to capable runners LeSean McCoy and Leonard Weaver.
The big thing to take away is still the attempts. Take the entire season, with or without Westbrook. When the Eagles run the ball 23 or more times in a game they were 10-1. When they failed to do so, the record drops to 1-4. With these results, it looks like its not so much the performance of Westbrook as much as it is how his presence affects Andy Reid's play-calling.
The Eagles have a good running game that they need to use. When Brian Westbrook was sitting out with injury, we found out just how good our running game can be because Andy Reid let the running game do its job.
As a result, the team performance of the Eagles was very strong in the games where Westbrook was injured.
My hope is that whatever prompted Andy Reid to run the ball more when Westbrook was not playing will continue to influence his play-calling now that Westbrook is no longer on the team. If that happens, the Eagles can continue to be one of the high flying offenses in the league.