Him losing is realistic for this fight, this opponent. But what's not realistic is him never winning a match. He's got the effort, plenty of conditioning, very strong tactical sense, is pretty good at reading his opponent's moves, generally has a good defence and counter. Add in that frankly, most amateur boxing isn't about KOs it's about points, so it doesn't matter as much as one might expect that his punches are weak. Not every opponent is awesomely talented. He ought to be able to out-point a lot of opponents and get a decent win-loss record.