Fish, IMO, has way more potential than Blake and Ginepri. Blake has a great forehand, and he's quick, but his backhand and serve is too average. He's done well. I doubt he's ever going to do much better than he already has.
I've been waiting for Dent to make a move for a couple of years now, and I've pretty much given up on him. Fitness is his biggest issue. You would think he's got the weapons needed to crack the top ten, but he's too out of shape, inconsistent, and lumbering.
Fish is also not the greatest mover on tour but I think his weapons are the type that can compensate for his weaknesses. He's got a huge serve, a great backhand, is pretty cocky, and seems to have an X-factor type flair for the game. He's got a lot of talent. He needs to strengthen up, get his movement up, make his forehand more consistent, and maybe get a new coach. He has the type of talent that I think a lot of elite coaches would be interested in tinkering with.