Thing is, though, he's a proud Welshman and many times during his career (not just during his international days) said he was happy playing for Glamorgan, loved the club, wanted to spend the rest of his career there, etc.
I think, in that last season, he might have got something of a siege mentality. Felt that everything was stacked against him - had loads and loads of bad memories. So he tried a move.
And sure enough, things started to go right as soon as the move happened. I think it was more a case of his bad luck running-out, as it surely had to eventually (for the time being at least - won't be presumptious enough to presume it won't return, maybe soon). That just happened to happen after he'd moved counties, for my money.
"Going stale" is a nice way out people like to use sometimes for my money, to create the illusion of "freshness" when it's not really there. Sometimes, by playing mind-games with yourself, you can make things better.
But as I say - I don't feel that's happened in this case. It's simply coincidence - his bad luck had to end eventually, and it ended when he changed counties.