Nope, can't do retrospectives like that, got to nail your nuts to the mast now.
If he comes good it'll represent sheer good luck. He's an aging cast-off with a very poor record at international and top club level. Nothing to suggest he'll succeed in the PL.
If he comes good it won't have anything to do with luck at all.
Finding success (and subsequently staying up) in a loanee who has no track record of scoring goals at any decent level in his late 20s instead of going out there and signing a proven goalscorer is just about the definition of luck. We're relying on pure chance.