Jordan Esco of Crimson and Cream Machine published a meticulous review of Oklahoma's recruiting classes since 2005 today in an effort to quantify the perceived decline in the Sooners' overall talent. It's the kind of exercise that leaves plenty open for interpretation, but the thing that stood out to me was the attrition along the defensive line.
My count of defensive linemen by class who didn't wash out at OU (i.e. left the program):
2012: 3/3 (No DTs)
Of the 24 linemen recruited by OU between 2007 and 2012, 13 did not leave the program (or haven't left it yet). That includes the 2012 class, which didn't have a single defensive tackle in it. The 2013 crop hasn't gotten off to a good start, either, as tackle Kerrick Huggins is heading to junior college and JUCO signee Quincy Russell has yet to make it to campus this.
That's how you end up with outside rushers like David King and Chuka Ndulue getting moved to the interior. It also sums up the end of position coach Jackie Shipp's long tenure on the Sooner sidelines.