Sumlin's days are limited in my opinion, 2016 is probably his final year. Texas A&M went from middle/bottom of the Big XII to same spot in the SEC. They have all the potential in the world...just need the right coach to channel it.
This article touches on the subject a bit, TAMU doesn't have a QB problem. I've mentioned this previously, when fRan was at TAMU he didn't recruit offensive linemen very well. Sherman immediately addressed that, all those guys drafted the last few years in the NFL...all Mike Sherman. Sumlin had absolutely nothing to do with this. Johnny Manziel had his knack for extending the plays along with the offensive line that Sherman built, which is how Texas A&M entered the SEC the way they did.