Williams among NFL's best defensive linemen

Editor's note: This is an expanded version of a passage that appears in Scientific Football 2006.

Defensive linemen have historically been one of the most underrepresented positional groups from a statistical standpoint. Sure, they get credit for sacks, but there are many other contributions they make that they don't get credit for, especially in the running game. One of my goals in researching Scientific Football 2006 was to create a series of metrics to try to help remedy this situation.

After compiling a season's worth of these metrics, it was clear there are a number of defensive linemen who don't get the credit they deserve. Below is a list of some of these underappreciated linemen, along with some comments about them from Scientific Football 2006.

• Pat Williams, DT, Vikings: Williams led all defensive tackles in the number of times he defeated an offensive lineman's block. In fact, Williams' 44 defeated blocks were nine more than the second-place finisher in that category. There were games when Williams was simply unblockable, yet he still didn't make the Pro Bowl.

Williams claimed that part of the reason he didn't make the Pro Bowl was due to an effort by some offensive linemen to keep him out, a voting conspiracy of sorts. Part of this may have been due to Williams' way of approaching the game. Williams says he hates all centers and guards and wants to destroy all of them.

I don't know about a conspiracy, but I will say this: The person or persons who pick the Pro Bowl injury replacements could have selected Williams to replace the injured Rod Coleman. Instead they picked La'Roi Glover, who had one of the worst success percentages of any defensive tackle. It makes you wonder about the entire selection process.

• Kendrick Clancy, DT, Cardinals: Clancy ranked first among defensive tackles in yards per attempt allowed. He was also second in success percentage and first in the SYPA (success percentage times yards per attempt) metric. With the Giants last season, Clancy also ranked second in the league in total run blocks defeated. He was like Williams in that there were games when he was simply unstoppable (including a game against Dallas, when Clancy single-handedly caused a fumble that the Giants returned for the eventual game-winning touchdown).

• Grant Wistrom, DE, Seahawks and Michael Strahan, DE, Giants: Wistrom and Strahan certainly aren't undervalued defensive linemen, but they deserve to be included on this list because of their ranking in the metric called pursuit plays. Pursuit plays are plays when a defensive lineman either chases a play down from the back side or runs at least 5 yards downfield to make a tackle. Wistrom led all defensive linemen with 20 pursuit plays and Strahan finished second with 19. These two are seen as exceptional pass rushers, but this metric proves that they do a whole lot more.

• Albert Haynesworth, DT, Titans: Haynesworth may have been the most disruptive defensive lineman in the league outside of Williams and Clancy. Haynesworth defeated a ridiculous 43 percent of his point of attack blocks, which was the highest percentage in that category among defensive tackles. His specialty was exploding into the backfield, something clearly shown by the 13 penetration plays he made, which were tied for second in that category. One other incredibly surprising metric for Haynesworth is that he also had 19 pursuit plays, which is something one would not expect from a man of his size.

• James Hall, DE, Lions: Hall is largely seen as a pass rusher but nearly all of his major run metrics were in the top four among defensive ends. Hall defeated over 35 percent of the run blocks directed at him. His 3.6 yards allowed per run attempt was good enough to rank him 11th in the league at his position.

• Mike Patterson, DT, Eagles: Patterson could easily make a case that he was the best rookie defensive lineman in the NFL last year. He defeated over 27 percent of his blocks (the 15th best percentage among defensive tackles) and he also allowed only 3.5 yards per attempt. If Patterson did this well last year when the Eagles were very thin on the defensive line due to injuries, he could be positively dominant if that unit stays healthy this year.

KC Joyner, aka The Football Scientist, is a regular contributor to ESPN Insider.
His latest release ("Scientific Football 2007") is available for a special preorder price at his Web site.