I don't know if people come back and throw with better velocity than before the surgery. Take Kerry Wood for example. In his rookie year, he was consistently 97-98 mph. Now, he's more consistently at 95-96 mph and topping off at 98 mph. But he's no longer bringing that fastball 98 mph all the time like before the surgery.

After Tommy John surgery, you have new ligaments which are obviously in better condition then the aged ones you were previously throwing with. As a result, In most cases, you throw harder.

I heard somewhere its also a stronger ligment.. :unsure :

i think Burnett hits that gun a 96 - 98 on a consistant basis

 

penny could also go up to 98 ... although hes more of a 95mph

 

Beckett is around 96 - 98 as burnett, but AJ hits that 100 mark once in a while and that thing just takes off.

There is a difference between the best fastball and the fastest one. I think that would have to go to Beckett, as sometimes it is downright overpowering. A.J.'s no hitter came as a result of a steady diet of fastballs, but was "Wildly effective" with it (9 walks). Having seen them develop in AA it was also Beckett who had the bigger advantage over the hitters then.