I'm gonna go out on a limb and say this is actually realistic. Most fighters never fight competitively again after a string of defeats, no matter how technically skilled they are, because they don't have a killer instinct to win. They've had it beaten out of them. Microseconds of hesitation, the slightest pull of a punch before it lands, the extra kg on the back foot and not adding momentum, it sabotages your best efforts because you are getting ready to defend before you've even swung.
His critical moment of hesitation happens right as he's stepping into the punch, swinging late and leaving himself open. If you've ever been in a fist fight you know you'll lose, you'll know the feeling.