I doubt it’s got anything to do with the GT football program. As others have mentioned, there’s no upside in leaving midseason for reasons related to football or job satisfaction (unless it’s a retirement, which I doubt). It’s probably for health or family reasons.
I hope Coach Eley is able to do a good job with the RBs. I’m a little concerned that his resume doesn’t include any jobs where he coached RBs in particular, but he does have extensive experience coaching college football, and his specialty seems to be the offensive side of the ball, so I’m sure he knows a thing or two about RB play.