Unless he brings the dozen or so NFL first rounders he has playing under him at Alabama, I doubt he'll make much of a difference.
The spread is dominant in virtually every conference. The few teams who can shut it down consistently—USC, LSU, Florida, Alabama—do so because they're stacked with NFL talent, not because they have figured out some schematic solution.
Oklahoma, for all its recruiting success, has struggled to develop elite talent in the secondary. Just look at NFL starting lineups today for evidence of that. I believe there will be one OU product (Quinton Carter, Broncos) starting this weekend for an NFL team. Mizzou will have two (William Moore, Falcons, and Kevin Rutland will get his first start today with Jacksonville).
When you recruit like OU does, it's flat out inexcusable to have so few players in the NFL. Granted, there are another few guys on rosters, but it's still not in line with the type of talent OU should have. When you play in a pass-happy conference and can out-recruit all but maybe one team, you should have no shortage of elite cover corners. OU hasn't. That's a failure on Bob Stoops' part, which is surprising considering he was a safety himself.