Full disclosure here, I'm a Leeds fan. Not here to troll or anything - just wanted to clear up around Kalvin. He did play CB for us in a 4 quite a lot under Bielsa but it was almost always in the first season, the season before the promotion season. That tended to be a bit of a last resort, the CBs that year (Cooper, Jansson, Berardi) were an injury prone lot. In a back 3 (which we always switched to when we occasionally played vs a team with 2 strikers) he would play as the third centre back naturally (Bielsa called the CDM role the 'third defender' regularly in press conferences).
From the promotion season onwards Kalvin only played CB in a back 4 in strange injury crises. He was always otherwise a CDM or CB in a three (and he didn't always end up doing that either, Bielsa started arranging the team in other ways when we used a back 3).
I think Kalvin would work well for your team. Mobile guy, good presser, can really ping a pass well. He's not the first good player who doesn't fit Guardiola's team, but it doesn't mean he's not good. Tbh I think their scouting team misunderstood who he was a bit based on Bielsa's system, but all that means is that he isn't Rodri. Loan in Jan, esp if Tonali gets banned, makes lots of sense.
