The running game is definetly not a concern.
I think the running game is definitely going to be a HUGE concern, at least for the first half of the season while Ronnie gets going. As I said when he got injured (mind you, I was just parroting some great experts in sports medicine), Brown is probably going to be called 100% by the start of the season, but his performance will be disappointing. That's the standard recovery process for Brown's injury these days. Normally, running backs do return to their previous level of performance, but it just takes longer than the "he's 100%" claim will suggest.
As for Ricky... well, he took a handful of snaps and got injured. I don't think we can say anything one way or the other about him.
Booker is an interesting player and I went out on a limb predicting great things from him this past season, but, unfortunately, Cameron didn't feel he was ready. When he was finally given a chance towards the end, I thought he did quite well. The new management have spoken very highly of him, so it'll be interesting to see how Sparano can get him involved. He clearly has some spectacular abilities, but tapping them isn't going to be trivial. It's not like just handing off to a power back...
So, all in all, I'd say I'm very concerned about our running game next season. There's a lot of a potential, but too many IFs for my liking:
IF Ronnie gets back to 100% by September.
IF Ricky can actually still perform (and not get injured).
IF Booker turns out to be great AND Sparano can get him involved.
If all of those IFs fall out the wrong way, we'll have a running game lead by a gimp Ronnie and some guy named Patrick Cobbs. That would get ugly pretty darn quick.