... You just described a FB.
We just gave him 100+ carries.
We shouldn't give our FB 100 carries. He doesn't make any plays that aren't there basically. Dude doesn't make anyone miss, and barely breaks any tackles. He falls forwards when he goes down. Okay thats nice. He isn't often LOSING yards, which is good. Him as a person and leader in the locker room is separate from his on field ability. Okay he can block. That's cool, but he isn't a weapon out of the backfield, so we shouldn't want him in on 3rd downs too often. Having them there just to pass block would be a tell. Him being in during 2 min drills or in clear passing situations was painful. Martinez was so clearly better in those situations. I'm perfectly happy having him in the backfield anytime we are running a 2 rb set. In fact that seems to be when he is at his best BECAUSE he is capable of running just fine, but can be that blocker like you said.
He was our 4th best RB this season. 3rd if you want to be nice and give him the edge over Allen. Martinez > Lyle > Allen/Fletcher > CJ jr