I know some people have criticized his blitz pick up. And while that is important, particularly for starters, you can work around that and eventually teach it. Teaching actual shake and bake or receiving skill is harder. As is kick off instinct. Larison wins in those factors. So to me he should be RB3. Just don't make him pick up the blitz till you are sure he can do it too much.
The main things to watch are Raridon, edge, LB. I would like Jacas to take steps forward. I am not looking for a leap forward in 5 days... but if he improves on a few things, I'd be happy. At LB. Just be consistently in the right spot. If they can't even do that, they can't can't be LB 3. If they don't know how to shadow a TE yet... they can't be TE3.