Simple. To keep the QB upright. It isn't ideal. I want to see the current starting OL enter the season as-is. That would mean they have shown the ability to protect the QB. If Guyton regresses (my biggest concern on that line. Questionable work ethic and character coming out of college), we could be looking a liability protecting the blindside of a now injury prone QB. That is a problem. Smith had some penalties, but has shown he can man LT if necessary. If the options are either allowing Guyton to find his rhythm and opening Dak up for injury, or shuffling the line, losing a bit in the run game but solidifying the bookends, I'm going with the latter. I don't expect Guyton to play as an all-pro this year, but we really need to see some improvement before declaring that the line is set.