Darryl Tapp was Seattle's best defensive lineman in 2009 as measured by EPA+, and by a wide margin. Plays he was involved in were worth 39.8 points for Seattle. That's more than Mario Williams, and just a hair below Dwight Freeney and Robert Mathis. This doesn't tell us the whole story, but it does add a little substance to Tapp's otherwise weak counting numbers.
That is one of a host of interesting finds found in Brian Burke's individual defender database. Another not too surprising fact: Brandon Mebane was better in 2008 than he was in 2009. In 2008, Mebane was among the cream of the crop. He ranked between Jay Ratliff and Jamal Williams for ninth in the NFL in EPA+. (I prefer EPA+ to WPA+ because it removes context) Mebane added 34.4 points. Colin Cole was Seattle's most valuable defensive tackle by EPA+ in 2009. He finished 15th with 25.7 EPA+. The big difference between Cole and Mebane, both 1-techs but in different seasons, is that Mebane contributed to both the pass and run defense. Cole contributed exclusively as a run defender. He had no sacks or quarterback hits. Mebane had six and 18.
The key to properly interpreting data like this is to combine it with scouting to create a total portrait. The aggregate of all run plays in the NFL is worth negative WPA, and so defenders that contribute to the run defense will tally high WPA+ and EPA+ values, but could be hurting their teams in ways that WPA+ and EPA+ do not properly measure. That's Colin Cole. That also accounts a little for Tapp's total EPA. Tapp is good, but not nearly as good as Freeney. Freeney contributes hundreds of pressures that are never recorded in the play-by-play. He forces outlet passes and double teams. So tread carefully. WPA+ and EPA+ are not definitive, but they're useful and yet another tool for interpreting the NFL.