The age of 33 still seems to be quite favorable for a short period of time. A good performance history certainly gets him good enough, but for injury history I think Napoli should be wary. They should be able to use De Bruyne well. His long injury history might come back if Napoli are not able to manage him. A 2-year contract is good enough to tie him down for the second year. I think Napoli can take advantage by reselling him. I think many MLS and Arab clubs want him.
I honestly don't know if DeBruyne is a winning move, certainly the fact that he was injured for so long is not very good, you risk taking a broken player who doesn't even play a game for 2 years.
In this case, unfortunately, it's a matter of luck.