According to Mattox:
The coaches are starting with the lineup that offers the best theoretical upside. If the reality of camp play dictates otherwise, they'll change it up. Pencilling in Hudson or Okafor unproven is inadvisable. They need to earn their spot(s) and will be given every chance.
Williams is money. The most athletic tackle in the league. With an offseason to add strength and size, look out.
Perkins is an average tackle, but a NFL level player at guard. You start him here and hope his plusses inside outweigh minuses from replacement outside.
Shackleford is being asked a lot and Notre Dame Nose Tackle Jarron Jones looms. It's his job to claim. If he doesn't, we'll see a number of folks take a shot here.
If Vahe gets more consistent in his pass pro (basically marrying his hands and feet), he's All Big 12. The Power game with Vahe/Perkins will be tight.
Tristan Nickelson, Battle of the Belts Champeen and favorite Longhorn project, is slated at RT. Omenihu (now up to 270, but looks 245) and Cottrell (now up to 260+) will test him and that class is Pass/Fail. We'll know his grade soon enough.
None of this is written in stone. And we'll see significant cross training and experimentation when Fall camp goes to closed access. Count on that. The OL is a big equation. Mattox is looking for the best sum total.
If you understand our new offensive philosophy - and if you'd like to, you should probably pick up Thinking Texas Football where we go in depth in very readable, easily understood terms with diagrams and everything - there are ways to mitigate problems at one tackle position with help from the TE, 3 step drop simple reads from 4 WR sets and slanted protections.
On the other hand, addressing interior breakdowns is almost schematically impossible once the defense understands you can't block them there.
This offense cannot allow quick interior pressure. That's death for everything we're trying to do and the quickest way to turnovers and an injured QB. Flanking Shack with Perkins and Vahe as security blankets makes a lot of sense. And it sure as hell tells you what we want to do in the running game.
This depth chart is clay. And I'm not convinced we see firm stone until weeks into the season.