Charles doesn't grapple often enough, he did score two tds against Azat and could not control him, but he also got knocked down by Azat who is barely a striker. There was a brief moment Charles took Azat's back and almost synched a rear naked choke, it's possible he could get Su via rnc.
Su sub defense is bad, but he also did scramble and sweep Schnell in round one and two . He's not completely out of water on the ground, he just has the worst matchups with grapplers, so does Charles. If Charles lets his ego get in the way and turns it into a kick boxing match, Su could beat him with his south paw stance, throwing 1-2 combos and his spinning kicks, constantly attacking the lead leg with calf kicks. Su is also as big as Charles and has a 2 inch reach advantage, fights long.
I think Charles is always a good play, when he faces guys who can't wrestle, are generalist/strikers but he also has very close competitive fights with those types, split with ode loss, controversial split with Zhalgas , and was getting tagged a lot by Van before the ko in rnd 3. And Van is a short fighter with short reach and manage to tag Charles with hard punches that almost dropped him.
It's possible Charles can steamroll here , but a lot of his wins end in decision, i don't know how confident i am that he'll try to exploit his grappling and not just lose a low iq fight.