Last week we took an introductory look at Seattle's offensive personnel groupings (here and here). The file I'll make available tonight breaks down the use of personnel groupings on first down. From this file we can make a few observations.
We notice right away that the "E" offense (2RB, 3WR) has been more effective than the "regular" offense (2RB, 2WR, 1TE) on first down. Seattle has used these groupings more than 100 times each on first down, so we have a good sample size. This includes at least 50 passes and 50 runs from each. From this, note that the regular offense (base offense) has produced only one TD, four INT and six sacks. The "E" offense has produced four TD, 2 INT and three sacks. "But where are these plays originating?" you ask. Good question. Seattle has used its "E" offense only 15 times in the red zone, compared to 35 times for "regular" personnel. And yet the "E" personnel has put up better scoring numbers.
The difference between regular and E personnel, at least in recent weeks, is simple. Regular personnel features Jerramy Stevens on the field. E personnel features D.J. Hackett instead of Stevens. Both personnel groupings are producing unimpressive per-carry averages in the run game (about 3.5 ypc each). But the E group is producing much better results in the passing game.
Note, too, that Eagle-20 (4WR with Mo Morris) averaged 7.6 yards per carry, while Eagle-37 (4WR with Shaun Alexander) checks in at 3.5 yards per carry. Seems as though teams are much more wary of the run when Alexander is the lone back in a 4WR set. This would make sense given that he is the MVP. When people see Morris back there, they probably play the pass a little more. Scroll down a ways in the file and you'll see that Seattle has been spreading the field on first down more frequently in recent games.
Note: Early in the season, Nate Burleson was with the regular group, Bobby Engram was with the E group and Stevens was not playing at all.