Here are some points to consider:
1) Les Miles was only in Stillwater for four seasons, winning 28 games. He went 4-7 in 2001 but averaged 8 in his last 3. He beat OU in his first season, where he went 4-7. He went oh-fer the next three.
2) He succeeded Bob Simmons, who went 30-38 in the 6 seasons prior. Miles was an upgrade, but he wasn't exactly night-and-day better.
3) Miles' successor, Mike Gundy, has won nearly 70% of his games since 2005. He's already the winningest coach in program history. Once can argue that Miles laid the groundwork for Gundy to succeed, but more likely it's because T. Boone Pickens opened up his pocketbooks and helped fund all the shiny new toys oSu has gotten over the past few years. Would oSu have the same profile now had Miles stuck around?
4) Kansas and oSu, as programs, weren't very different from each other 15 years ago, but they have since veered off in opposite directions. The Cowboys are perennial B12 contenders, and KU is lucky to win more than one conference game a year. I don't think Kansas has a sugar-daddy like Pickens, but maybe some of their boosters would be more inclined to invest in the football program if Miles gave them something worth investing in. He has won a national championship and coached in another, so maybe they're serious about making KU football respectable.