How can we in the middle of the pack in "adjusted sack rate" (I've been around football in one form or another for 25 years and never heard of such a thing), middle of the pack against opposing first and second wideouts, tight ends and running backs (essentially everybody who catches the ball) but 6th against all other wide recievers?
Do you have a link so I can read that?
The stats are from Footballoutsiders.com. They have explanations aplenty. The relevant ones to this discussion are "defensive" and "defensive line".
Sacks: Looking at the total number of sacks isn't particularly relevant, since it doesn't take into account how many opportunities there have been to actually get sacks. That's why we all talk about a quarterbacks completion percentage, not his total number of completed passes. Since you don't get sacks (by definition) on running plays, the "sack ratio" is the ratio of total sacks to pass plays seen by the defense. What FootballOutsiders do is then adjust that by the down, distance and opponent to better enable comparisons between teams. (Technically, their "adjusted sack ratio" is a better predictor of sacks against an opponent than just "sack ratio" -- which is still much better than just using the total number of sacks).
Considering that some teams see more than twice the number of drop-backs as other teams, at the very least we need to look at sack ratio (like completion percentage for QBs) to make any meaningful comparison.
Pass defense: Instead of just looking at the total number of yards a defensive gives up, it can be interesting to look at how many yards have come against the type of receiver. Is it the other teams #1 reciever all the time, suggesting a lack of a #1 cornerback (or scheme to provide support) -- or is it, as has been the case with Miami for the past many years, the TE who inflicts the damage? Footballoutsiders.com take each individual play and assign the pass to either the #1 receiver, the #2 receiver, a TE, a RB, or "other".
As with sacks, it often makes more sense to adjust the yardage for the total number of passing downs (just like we often look at yards/attempt for running backs). Footballoutsiders.com then takes this a step further and adjusts for opponent, down and distance. E.g. it's a lot worse to give up 10 yards on a 1st and 10, than on a 3rd and 15.
Even though we're ranked 8th in total pass defense, the teams are actually clustered quite tightly around the middle of the pack, so the difference between us and "average" is quite small. Our rushing D, on the other hand, is A LOT better than average -- and actually fairly close to #1 (we're ranked 5th).