True but If you have a great tennis talent (which Tommy has), you can always come back even if you are a bit old. Talent doesn't disapper with injuries. Look at what B. Baker did this year after being so unlucky with injuries in the past.
True, his talent isn't in doubt. But he had so many injuries and surgeries that you couldn't really blame him if he had given up long ago. It's amazing how he kept through it all and is still playing at such a good level.
It'd not be an exaggeration to say Haas is one of the unluckiest players ever to pick up a racket, as far as injuries are concerned. His injury record is just scary.