Lane makes $9 million/year at Ole Miss and is winning 9-10 games a year at a school that does not have a great football history, and is a folk hero there. Sark is making $10.8 million/year at Texas, and currently doing great, but will be on the hot seat the minute he misses the CFP a couple of times and perpetually has to deal with all the politics entailed with that job. I'd say Lane's got a pretty good opportunity at OM, especially considering that he's at a place that lets him show his personality.
Sark currently has the more prestigious job, sure, and post-personal problems is more buttoned up than Lane is, but I wouldn't take that to mean that Lane is underachieving.