How Successful Could Mardy Fish be in his Return to Professional Tennis?

Mardy Fish has recently reentered the waters of professional tennis, playing doubles in a challenger and planning to play Indian Wells.  At this point it isn't clear whether his comeback is a short term thing, or if he's seriously committed to becoming a full time pro.  Assuming his anxiety and other health issues aren't a factor, Fish is fully capable of making his return a successful one. 

Fish is currently 33 years old, and didn't play on the tour during the 2014 season.  He had been playing some of the best tennis of his career during his last few years, and likely feels he still had more to give.  Fish certainly isn't young, but there are several other players still having success in their early to mid-thirties. 

Before his shoulder injury sidelined him, Tommy Haas was still going strong at 35.  Federer, Ferrer, Lopez and a handful of others show little to no signs of slowing down, and all are near Fish in age.  Benjamin Becker (not exactly a superstar during his twenties) is currently top 40 in the world at age 33.

To become a top 30 pro once again, Fish would have to be fully committed in terms of rebuilding his fitness and practice regimen.  He's always had a strong serve, and he'd need all the easy points he can get in his comeback.  The key for Fish would be how hungry he is to make another serious run on the tour.  If he just picks and chooses a handful of tournaments, it would be tough for him to gain the match experience necessary to compete at a high level.  No matter how well someone thinks they're hitting the ball in practice, it's extremely difficult to sustain a high level of play in matches without being match tough.  Fish certainly knows this, but whether he wants to return to the grind of the tour remains to be seen.  However, a fully committed and healthy Fish would certainly be capable of returning to the top 30.

Were he interested, Fish could likely become a successful doubles player as well.  His game is well suited to it, as he's always had great volleys to go along with his solid serve.  In his dabbles into doubles during his singles career, he managed to reach the semifinals of Wimbledon and win a Masters title, amongst other successes.  We can't yet know if Fish would be interested in travelling around the world as a doubles player, but it could be a great fit for someone of Fish's talents. 

Fish's return could prove to just be a short stop, with Fish wanting to end things on his own terms.  However, more success awaits Fish if he wants it, and he may find the possibility too hard to resist.