Just watching the game back now as was out yesterday. We concede so much ground territorially when Kelly is on the pitch. Hamer isn't a great tackler but he faces up the opposition on their own half. Kelly was sat on the edge of our D. To be fair to him though part of that might have been down...
The other thing that might be a benefit to him is that he was never fast so he's not necessarily having to change his own game too much to account for reduced pace.
I was surprised he was released. Incidentally, I've been watching old episodes of Crimewatch from the 80s on YouTube, one of his murders was covered (the one in Enderby). Horrible bastard.