Personally I think he is worth a 1st. He's that good. I'll go as far as calling him just as good if not better than Foster. He's more explosive and can run through arm tackle better than Foster. He's also more sure footed. You don't see him slip on cuts like you see in Foster. He's also underrated in the passing game. He was on pace to a 1500+ yds season and 2nd in yds per carries while Foster was out earlier last year.
But his injuries and limited carries this season hurt his stock value severely. If we lose him and he starts full time for another team, expect Tate to have a breakout year.