It can't be understated how much better the OL blocked yesterday. They went to a more power scheme and got some guys out in front of the RBs. If they can keep that up then it really might not matter if it is Randle, McFadden or Michael.
Yes, the blocking was the key to the improved running game. They did make changes in the scheme and they had improvements from individual players. Collins is terrific physically; whereas, Leary never should have returned from the Groin injury when he did because it was obviously not close to 100%. Martin had started to look like himself in the Pats game and now seems to finally be past the neck injury that kept him out of the preseason and limited him early in the regular season. Hanna was a big part of the running game last season and he was back so I assume that helped; although, I didn't focus on him.
The threat of having a QB that would throw the ball also appeared to back the defense off from loading up against the run.
The Seahawks will be difficult but if Dez returns they'll likely double him which will also help the running game.
I agree that any of the RB can probably have success as a runner if the blocking is as good as it was in the Giants game. I suspect that pass blocking might be C-Mike's limitation.
The biggest issue with the RBs this year as compared to last is that none of them are playing ST; whereas, last season both Randle and Dunbar played ST.