Cameron just hasn't learned how to play on a bloke like Grimes, and let's hope he never does.
Charlie is pretty good at out manouvering or outmuscling many, but not Grimes. Charlie is good over head but Grimes is better. He's playing into Grub's strengths. Cracks the sh!ts because it's not working for him as it usually does against lesser mortals.
Even his coach said before the final against us that Charlie needs to find other ways to get possessions as what he's doing doesn't work against this bloke (along with telling the media that Grimes was holding on all the time and the umps need to be alert for that, when photos show that it was Charlie doing the holding).