Think Ewers and Xavier just aren't on the same page--were early on but some break downs along the way have offset any kind of timing they established. Ewers absolutely throws receivers open or will throw to a spot--which is why it looks like the ball is out in nowhere when they miss. He's shown early on that he has plenty of touch and anticipation, but when guys drop passes and every play is the touchdown long ball, then both parties over compensate.
There's also some bad play calling--mix in some intermediate routes, quick slants, cuts and come back to the ball. These are all plays where quick receivers can absolutely shake coverage. I think Xavier can operate in a phone booth but on deep balls, really isn't asked to when it's just go deep. That's also not fully utilizing his skills--move him around. I think Xavier's equivalency in the college game, or could be, is more Marquise "Hollywood" Brown. I'd probably really look at Brown's utilization when he was at OU (burns the eyes) and how he got the ball all over the field.
Furthermore, wtf is Sark doing--when the qb is off, how about building him up to the deep pass rather than relying on it. Get the offense moving--if the defense wants to give up the underneath, take it. It'll tire them out more than just running deep for 3 and out and then punting, but force the safeties to back off--and utilize some screens to open the run game. Sark and Ewers got in a rut and the offensive play was caught on a short loop for awhile during TCU. I don't know what to do about blitzing up the middle except....
Vary the damn snap count--like a bunch. Practice it so the line doesn't jump but vary it more and collect penalties. TCU was timing their rushes in anticipation. Vary it a few times and they absolutely would've jumped offsides. Instead they changed it after that game, rather than during. But again, practice it so that the line doesn't move.
Random thoughts before giving up on Xavier. I go knee jerk about letting him walk but he's a top risk that could offer a lot of benefit if everything get's ironed out. And yes, you can work on catching over the shoulder throws or opposite shoulder throws. Just do it regularly. The other thing that has been great about Worthy is that he pretty much has stayed healthy, which is a bonus that you can't guarantee in the portal.