On potential alone, Zach Banner has a lot to offer the USC Trojans. His physical talent is something to behold. At 6'9", 330 pounds, he definitely has the capability to bring the power once he fully develops.
"Once he fully develops" being the operative term. Check out Banner's senior highlights on Hudl, and you can see there's a lot Banner has to figure out before he's ready to contribute on the Division I level. He has the body and the frame to be a force, but there's not quite enough push there yet.
Banner doesn't look terribly explosive off the snap, and seems to rely more on his overwhelming frame to win his individual battles. I wouldn't say he's coasting, but he definitely doesn't jump out at you like most physical talents do with their tape. It's not like Class 3A Washington football is filled with top defensive prepsters either; Banner just does enough to win his battle and move on.
Banner has one big issue technique-wise: He plays upright way too much. That works fine in high school when you're pushing guys who you've got 100 pounds on, but any defender with a good bull rush is going to push Banner on his heels or force him to give up way more ground than he should. And it won't even begin to describe how vulnerable Banner is in pass protection--playing this upright is a good way to get blown by or knocked back. The man has to learn to squat in his stance.
Generally, it just looks like he has more fat than muscle on him. Banner just seems to struggle to keep the burst going when he plays. You can see him sort of slow down as the play develops and doesn't seem to possess any regular agility. He looks like a player who needs a great deal of conditioning before he can be an every down offensive lineman in college.
I like Banner's potential, but he's not quite ready in terms of technique to be an immediate contributor. That's tough for USC, because with Matt Kalil departing, they do need a tackle. Aundrey Walker is a massive human being, but he lacks the agility of Kalil unless he slims down a bit.
Banner will probably redshirt with Walker and Graf locked in as the starting two tackles and at least three more capable backups to fill out the two-deep. Since neither Walker nor Graf are seniors, Banner should have plenty of time to develop into a devastating tackle talent.