I've been thinking more and more about the issue of too many snaps for Jones and Ninkovich, and I'm wondering how much of it is a little overblown. Of course my preference is to have them spelled a bit more often, keep them fresh, etc. It would help them be more effective per snap and it would mean we found some talent behind them which is always good.
But last year, when they seemed to slow down, we were operating with rookies getting all the snaps at DT. While I think all players are susceptible to overwork, rookies seem to have an actual wall that they hit, on account of it being a long season from combine training to a longer playing season than they're used to. Combine that with the fact that Talib went down early in the Denver game, Dennard's shoulder was hurt, the captain of the defense was out and we had one good safety, and there was no way Jones and Nink were going to have enough time to get to Peyton Manning (who is very good at getting the ball out quickly).
Again, finding some guys to rotate in for them is a plus, but I'm not sure the issue last year was them being worn down as much as it was the defense in general being beat up and incapable of covering the best statistical offense in NFL history for longer than a few seconds.