He was put in the jersey before he'd picked up the skills he needed. He was a big name convert so it was the right thing to do though. He's big enough and hard enough to take it.
Much is made of the fact he came off concussed. YAAAAAWN so what? He's been concussed bafore and will be again. He's been tackled harder and faster by bigger men than were on that field. League has nothing like Jonah Lomu in his prime and Gareth had that experience. Brought him down a few times too if my ropey memory can be relied on.
Gareth was injured because of Gareth's inexperience not because he had the temerity to wander into a game played by superhumans.
He needs to learn League quickly and unlearn bits of Union. Only because his age is against him and he has little time left.
There'd be no point in sending him to SWS to ply his trade, because half our team are union converts on their first year of League too.
From what I've seen, if he can CONVERT his existing skills to this code (and I've no doubt he can) League holds nothing for him to fear.