Defensive tackles are often the most difficult defensive players to grade because they don't have the statistical highlights of their brethren. Defensive ends can tally sacks, linebackers can rack up tackles and defensive backs can collect interceptions and passes defensed -- but defensive tackles by and large don't have a standard statistic or two to lean on.
That is one of the reasons I enjoy breaking down tape on interior linemen. The performance metrics I use gauge dozens of areas unmeasured by standard play-by-play sheets, and this is especially helpful in quantifying the level of play for blockers and defenders in the pit.
It can even help those players who are already known as being top prospects. North Carolina Tar Heels defensive tackle Marvin Austin certainly qualifies as one of these (see Scouts Inc. analyst Steve Muench's post from last week), but the metrics show four specific areas where Austin has superior skills: