...has done and will do this coming season. You might start out guarding a particular player but after 2 or 3 switches in a possession you end up guarding a totally different guy.
In the NBA you often see pre-switching employed by coaches where guys intentionally start the possession guarding a mismatch so when the offense does a ball screen you get the defensive matchup you want. I wouldn't be surprised to see BYU doing some of that this season mixed into their Peel Switch scheme.
Defenses have evolved along with offenses and defenders have to be able to switch and capably defend multiple positions, including smaller guards defending in the post. Baylor guard RayJ Dennis was very effective last season taking opposing guards down into the paint and posting them up and getting easy buckets because guards are horrible post defenders. It's a growing trend and defenses are having to adjust to keep up.