Daniel Thomas is a physical specimen who is natural able to make things happen with the ball in his hands when he gets out into a little bit of space where one-on-one tackle attempts happen. That's why he succeeds in the passing game. There were times the Dolphins were able to play to his strengths by running him to the outsides, where he tallied 162 yards on 35 carries (4.6 ypc) in 2012-13, versus 569 yards on 165 carries (3.4 ypc) between tackles. He was consistently more efficient on outside runs in both seasons, and cumulatively more efficient as well.
As for getting better the more he carries the football I find little evidence of that. If you're going to delve into the realm of statistical analysis you have to do it right. He only had 10 carries in 2013 on attempts #11+ of a game. Yes he grabbed 66 yards on those 10 carries but the sample size is what is important there, because 55 of those 66 yards came on ONE run. So for the other 9 carries he gained only 11 yards. And in 2012 he averaged 3.4 yards on 16 carries that were attempt #11+ of the game, versus 3.6 yards per carry on attempts #1 thru 10 of the game. So basically this theory that he gets better the more carries he gets is based on ONE run, whereas the rest of the runs (25 runs for 65 yards and a paltry 2.6 yards per carry average) suggest the exact opposite.
Thomas has become a good teammate and a hard worker, and he still does well when you get him out into space. But he has no vision, bad instincts, non-ideal pad level, is too prone to being tripped up in traffic, and his skill set works at odds with his physical qualities. You don't HAVE to cut him right now. You might as well see what the other backs have to offer. But I wouldn't hold your breath trying to claim value out of him.