Your center position is pretty weak. Splitter was an absolute mess in the finals and can't be on the floor against small ball if Pau is your PF.
Hm. I disagree with you vehemently, absent Splitter's poor finals. But it wasn't just splitter who played below par during that series, and if you use his starting stats from last season, especially as it went on, he was one of the better centers in the league. A good man defender, decent rebounder, and elite finisher (for the position).
Small ball obviously Gallo slides to the 4, but I don't see the reason to play it much. Jonas and Splitter are both starting caliber 5's, with Jonas poised to make a big jump forward next season.
I agree with everything in your first paragraph other than he was "one of the best centers in the league". Best what? One of the best 30 centers? Sure. Seriously though, I actually like Splitter a lot as a player*. But neither he nor Val are a top 15 NBA center and this is a 25 team league. So I'd say your center position is relatively weak. And if you get matched up against a well constructed team that goes small ball with Lebron, Durant, or Melo at the 4... Pau and Splitter can't be on the floor together. Ask Pops.
I do see what you're trying to do here and I like the frontcourt size you've got going on (typically a winning CB Draft strategy), but I'm just pointing out weakness where I feel it exists.
I agree that Gallo could slide to the 4 in small ball and I like that a lot about him on this team. But that also means you've got 3 of your top 5 picks playing one position (and some backup PF). That's why I think Val should go. I say Val because I like Splitter, but if you are higher on Val, maybe see what Splitter's trade value is around the league.
*You can probably find posts from me that was ok with some kind of KG for Kawhi+Splitter trade after Rondo went down before Kawhi Leonard became a household name. I do like Splitter a lot.