Would be surprised if he has much value based on what he's done so far. Our system really rewards runners with great balance because players with balance (Golden Tate, Marshawn Lynch) are a lot harder to bring down. Turbin has maybe the worst balance I've ever seen, he is an arm tackle waiting to happen and on kickoffs he struggled mightily to break the 20 yard line because he'd often fall down on his own just from trying to make cuts at full speed.
If he has any real value in the NFL, it might be to a pass first team that gives him big holes to run through on Mike Holmgren's patented 3rd and long draw plays. Teams that intimidate with the pass and then audible to run when they get formations they like. But on a team like ours that runs in obvious running situations and asks their RBs to break some tackles for tough yards, Turbin just doesn't fit.
Also, with Lynch's big cap hit coming in 2015 we should expect this to be Lynch's last year in Seattle. Would they really have Michael rot on the bench for two years and then step in to start in 2015? Seems unlikely- I expect Michael will probably be promoted to #2 RB this season. Then it could be a battle between Ware and Turbin for the #3 job. Ware fits our scheme infinitely better. So I wouldn't be surprised if Turbin fails to make our next 53 man.
With all that said, if I could get a 7th for Turbin right now, I would take it. It's not that I think he sucks in every system, but I just don't think he fits what we do, and one way or another I think his days in Seattle are numbered. I wouldn't be shocked if he catches on elsewhere, he does some things well, he has a great attitude, and he's fast.