That is a tough one. I dont think the punch Groves landed on Froch would have dropped Marvin or had him wobbly when he got up. Kd's are not always a testimony of ones chin since many kds are a result of getting caught off balance and nothing to do with chin. Hagler was never really hurt bad at anytime in his career. The only time he went down was against Roldan and that was not really a kd even though ruled as such.