Gates isn't the most talented tackle in the SEC, but his athleticism helps set the offensive line. Someone has to play left tackle, and John Theus wasn't ready to take over that spot in 2013. Gates has steadily improved during his time at Georgia. Even if he didn't start at left tackle, Gates would start at right tackle or either guard spot (he played right guard this spring). In many ways he's Georgia's most diverse lineman, which mean he brings tremendous value.
Theus is probably the better long-term professional prospect, but at this moment Gates is the better player. The good news for Georgia is the depth along the offensive line. When Gates arrived at Georgia he played right away as a true freshman. The offensive line was solidified with his appearance in the starting line up.
Four years later Georgia fans wouldn't swap Rogers for Gates. The entire episode just goes to show that recruiting is part art and part science. In this case Georgia was very fortunate to lose out on the combustible Rogers for the steady Gates.