Kessler had most the rounds after the 3rd. It could well be true. Nigel Benn has blamed over training for a loss before.

Iv seen other fighters mention how they will only spar for 2 weeks before a fight because it takes the fight out of them too much if they do any more.

It could well be true. He was looking powerful before hand against Green and Magee. Blasting Magee away quicker than Froch and Bute.

I dont think Kessler is finished but he has had a knock on his ambition now. Look how one win has turned Frochs career round. If he had lost to Bute I don't think Froch would have carried on. I don't know if Kessler is maybe struggling with the weight.