I dont think he's the savior by any means, and I don't think he improves the offense with his rushing between the tackles. I think its mainly his presence that greatly changes dynamics for defenses. This entire season no LB feared getting burned by moss/Singletary in a dumpoff or screen cuz any LB can take a decent angle and catch moss/Singletary. So really there wasn't that respect factor, LBs could crowd the line, blitz, harass josh etc. Now comes brieda, hes not a stellar ball carrier up the middle, but every LB in the nfl knows they can't catch brieda in open feild. Brieda is extremely dangerous on screens/ dumpoffs cuz you think you have an angle on him and he's already gone.
Brieda makes LBs have to think about one more aspect of the bills offense and that in itself is very valuable.