Bob Stoop's decision to retire as the coach of Oklahoma after 18 years was nothing short of stunning. Though multiple reports indicate the longtime coach was ready to hang it up and live his life, it doesn't make the announcement any less shocking or the timing any less interesting. 

Like any coach who's been in the same place for 18 years, Stoops' legacy will be complex. He's the winningest coach in program history and coached the Sooners at a high level for almost all of them. Only four times in those 18 years did Oklahoma drop below 10 wins in a season. Each time, Stoops reinvented himself and elevated the program back into the national spotlight the following year. He never had a losing season in Norman and won a national championship in 2000-01. 

However, Oklahoma had not played for a national title since the 2008-09 season and were beaten soundly by Clemson in the College Football Playoff semifinals two seasons ago. It's entirely possible the Sooners had hit their ceiling under Stoops over the past decade. 

Stoops also (deservedly) landed in some hot water for his handling of the Joe Mixon punch video -- Mixon was suspended for the 2014 season, a decision Stoops himself later said would not have been enough today -- and bringing in wide receiver Dorial Green-Beckham, who was dismissed from Missouri following an alleged domestic abuse situation. 

These are the things people will remember about Stoops. All the same, he had a significant impact not only Oklahoma football, but all of college football. So with his retirement, the college football world -- from players, coaches, media members and more -- released an outpouring of support.