The video clearly points out the reason why Pead doesn't play regularly in the NFL. One whole season, six minutes of Pead-specific tape, two broken tackles. For an NFL RB, that's simply not acceptable--especially on a Jeff Fisher-coached team. You can't go two plays of Zac Stacy running the ball without two or more broken tackles.
Any comparison to Marshall Faulk is ludicrous. Marshall Faulk ran like an NFL back--Pead doesn't.
Pead's great for those check-down, RB over the middle passes--did well in those (not as good as Faulk, though). In a typical Schottenheimer driven offense, that may be valuable enough to keep him on the roster. I'll take Zac Stacy and Tre Mason running the ball and, I'm willing to bet, so will Jeff Fisher.