JC is the best all around back in the stable, but he isn't doing the team any good from the tub. This is a reality for guys who run like he does. He gives it all up, gets hit a lot, and thus gets injured. Either change your running style or have a short career. Kid is a fighter, we all love that. He needs to spend the entire off season healing and strengthening muscle (not necessarily bulk) to help protect his joints. That or maybe see James Harrison's acupuncture guy.
Snell is, indeed, too slow but its nice to have a hammer once in a while. An interesting aspect of his game may well be his pass pro. I didn't watch it much but I recall some folks saying he was pretty good at it. If correct, he should also work on his hands to make him a legitimate threat to catch rather than blitz pick up. Not sure he can add any speed, but he should work with a speed and agility coach the entire off season.
Samuels is interesting change of pace guy. It was well known when he was drafted he was more of a pass catcher than a runner. He did not get a lot of running reps at NCSU and I am not sure he will pick up the instincts at this stage of his game. Not saying never, but unlikely without a lot of live reps and there arent many chances for those at this level.
Whyte is absolutely electric - I love his speed and shiftiness. He looks like a back in the open field, but he is not stout enough to just drop his shoulder and drive ahead for a hard yard or two. I don't think he can hold up to 25 touches a game for an entire season, however he can also return kicks/punts so that helps his stock.
I said in another thread that they should use the 2cnd and comp pick in the third for a WR and a RB in no particular order. Depends on how the board falls out and how FA falls out. But without a doubt, the team needs a more all around RB and I would make it very clear that the starter job is wide open going into camp.
But - make no mistake about this...the running game will get a boost simply by having Ben back in the game. Running against 8, 9, and even 10 guys in the box is never going to work consistently.