I've been holding slightly better defense and I win much more easily on Offense with more JTR in my Arena. CLS had more viability to stand up to NS and him and rHanz ability to ignore zombie taunt went a long way, the typical Thrawn in the mix was a good counter as well.
The JTR teams I face are a joke, I mean, on defense it's tough, but the one guy I talk to in my Arena who also has JTR said she died from Plague without ever being hit - and that's my NS team on D.
From one point of view - it might simply be that CG wanted to make sure there was a viable DS team for Arena, and if so, bravo, NS works and easily countered themselves.
From another point of view JTR isn't really shining, IDK, if I'd put my resources into her I'd be a little sour too. Sure, Arena isn't the only mode in the game, but it does partially define a toons worth.