If you really prioritize building an arena squad, it’ll make a huge difference. Right when JTR came out, I decided I wanted to hop on board that meta. Once I had the gear, mods, and zetas in place, I was finishing in the top 50, whereas before I rarely cracked the top 200.
In the meantime, I’m still running JTR, and haven’t invested anything in keeping up with emerging metas. Lo and behold, my arena rank has slipped to where I need a little luck to finish in the top 100. There are lots of ways to invest your resources in this game besides arena, and that’s what I’ve been doing. I’m content with that. At some point, a new meta-defining character that interests me will come out (I’m waiting, Jedi Knight Luke!), and when one does, I’ll adjust my priorities.
Anyway, you can move up in arena if you dedicate the resources to it. It just means less resources for legendary farms, etc.