Head coach Kirby Smart has mentioned many times that UGA has a lack of depth. One way to overcome depth problems is cross-training the offensive line. That is, having lineman and learn more than one position.
The coaching staff has emphasized throughout spring practice that trying to predict playing time by observing who is taking reps with the first, 2nd or 3rd unit will not produce accurate results. For example, the 2nd unit left guard may not be the first player to substitute at that position. In many cases, another starter may move to that the open slot while a 2nd unit player comes off the bench at another spot along the offensive line.
Listen to Coach Smart explain the process in this video:
Uploaded by Bulldawg Illustrated on 2016-04-01.