What those stats tell me is that the players we have do have the quickness/athleticism to stay in front of their man in one-on-one encounters, but don't have the awareness and decision-making capability to navigate the complexities of pick-and-rolls (especially when one action is used to set up a second and third action).
Stotts has generally used a basic switching scheme to try and limit wide-open threes. The downside of that was creating bad mismatches on switches, like Lillard on Draymond Green or Kevin Durant. Stotts started changing his scheme in the past month/month and a half to do some partial hedging rather than switching (a thing some on this forum have been excoriating Stotts for not trying) and the result has been wide open three pointers as the primary defender dies on the screen, leaving the hedge ineffective (because it's not a hard hedge--Portland doesn't have the athletic bigs required to have them jump all the way out on a three-point shooter and then recover).
As far as I'm concerned, what all this shows is that Stotts' hands are tied: when you have bad defensive personnel, there isn't a scheme that will turn them into an adequate defense. What the isolation number suggests is that maybe this team would have been a solid defense in the '90s or '00s, when there was far less movement, screens and far more one-on-one action. Nowadays, defensive ability is not measured quite as much by being able to lock a guy down one-on-one (though that's still a nice ability to have) and more by the awareness, instinct and split-second decision-making to navigate one action after another without making even one crucial mistake. From what I can tell, by watching and the statistical evidence, Portland doesn't have a lot of good defenders in that respect.
