Its a huge plus for certain fighters. I think of Ray Leonard when discussing this! Ray was in my gym for his 5 or 6th fight (New Haven Ct) and he was an outstandng athlete able to tumble on matts and run and jump like a deer!
Eye hand coordination is a huge advantage to have in any sport and in boxing the boys with hand speed all have it!!
There are successful men that aren't equiped with these gifts that have done very well but why not have as much advantage as you can!!! Big + for athleticim in my experiences! Ray