effectivly defending a punch is not so much to do with quick reflexes and timing and judgement.

Do you have attention to detail? :P

Being good in goal might indicate you would be good at reading a punch though, not all that similar with having a punch thrown at you but you use some of the same qualitys.

Boxerjl is doing well for some one with out a trainer but he can only go so far doing what he is doing, you can not be a serious competative boxer Amatuer or Pro to a high level with out a trainer.