Offensive Football existed BEFORE Mike Leach and it would behoove some to understand that. The whole "System QB" thing really started when collegiate offenses started getting diversified back in the eighties. You had the BYUs and Houstons, schools that were cranking out QBs that put up huge numbers, but in the case of David Klingler and Andre Ware, they were unmitigated busts.
The difference between BYU with Jim McMahon/Steve Young and Houston with Ware/Klingler is that BYU's guys had the actual physical talent to succeed in the NFL, while Ware and Klingler's flaws were hidden by the scheme. Ware had arm talent, wasn't accurate, wasn't a great processor of the game. Klingler, outside of being drafted by the Bengals was a guy that took far too long to get rid of the ball and didn't throw with anticipation. Go look at Mike Leach's QBs over the years, there's a reason NONE of them ever succeeded at the next level, most couldn't even last past their first training camp. They usually had decent physical tools, were higher end mentally but in the NFL, marginal arm talent loses you football games more often than not. Guys like Lincoln Riley have done better with their guys, but you can argue that their offenses are a lot more balanced than Leach's ever were and that those QBs are better prepared for the pro game.
There are other schools whose scheme benefits a specific position group and personnel departments are wary of those guys, because of the fact that you get more busts than stars. Penn State tailbacks in the 80s and 90s were running behind pro offensive lines at the college level, most of them fell apart once those giant holes disappeared. There's a reason why Larry Johnson slid in the draft, people saw him and thought he was another Curtis Enis or Blair Thomas(I refuse to put Ki-jana Carter there, he was consistently injured). Wisconsin is similar in having highly productive tailbacks not be the same at the next level. Michigan State had a little run of linebackers in the 90s that were highly touted, and most of them busted out, mostly because people realized that if you were a good LB in that system, you would get plays funneled to you, so your tackle numbers would be inflated.
