Here's from teh Wiki's
Mustain was one of the most highly decorated high school football players in history, winning every national player of the year award, and was recruited by nearly every major college football program in the United States during the 2005-2006 school year. He played sparingly in his first game at Arkansas, but was named the starting quarterback by the second game of the season and achieved a record of 8–0 as a true freshman starter.
From teh Snaggie's....he also threw for almost 4,000 yards and 47 TD's as a senior. After leaving a fricked up situation at Arky, he went to one of the elite programs in the country. Apparently, his talents didn't translate to being effective at the D1 level. Happens hundreds of times every year in college ball...and in the NFL. He couldn't make it in Canada or the Arena league so I'd say that was probably the case.