It's not that the modern D can't defend it, it's that the modern D has to give something up with the way the game is called, so they give up midrange shots. They're inefficient unless you have a player who excels at it. If you have a player that can efficiently score at all 3 levels (3, midrange, paint) you've hit the jackpot. If you don't have that type of player, your offensive scheme should be to get as many clean looks from 3 and in the paint as you can.
Depending on the location in the mid-range, the NCAA average is right around 35%. Utilizing eFG, you'd have to shoot around 24% from the 3 to be more efficient than an average Div 1 mid-range shooter.
Specifically for OU, we we're more efficient from the left elbow and left baseline compared to right elbow and right baseline.
Left Baseline: 17/44 = 44.7%, NCAA Div 1 Average: 34.4%
Left Elbow: 15/34 = 44.1%, NCAA Div 1 Average: 35.1%
Right Elbow: 16/55 = 29.1%, NCAA Div 1 Average: 36.5%
Right Baseline: 16/48 33%, NCAA Div 1 Average: 34.1%
You can view shot charts here and compare teams, pretty cool site:
https://cbbanalytics.com/tools/shot-charts