I think Jazz at #9 had more to do with Simpkin than it did with Jazz. Something about him basically being MOTM against Penrith, running the ball often, and then the next week running it once, definitely ticked Seibold off. Benching him was probably just giving him a lesson, and he was more involved as a result.
I don't think we can afford starting Jazz at lock against better packs. Jake / Tevaga / Taukeiaho were absolutely burnt by AFB, Brailey and Hazelton in the opening 20 minutes of the Sharks game. Jake, along with slightly larger middles in Lodge, Aloiai, etc, are better suited to shoring up the middle in that opening 20. Tevaga doesn't have a strong enough running game to offset Jake's ineffectiveness running it then too. Without a strong running game in the opening period, we are constantly behind for the rest of the game.
For me, I think running Tevaga off the bench is our best option, like the Warriors did for most of his career. The game is a bit faster then, and Tevaga can do his best work against a less energetic middle. Same applies for Bullemor in my opinion, as Lodge is comparatively rubbish off the bench.