IMO Wells and Spear lack quickness just like Darby and Puckett, esp on defense. JP is just short, short.Sometimes Wells and Powell or Spears are getting posted up by bigger guards or rebounded over but they are mostly getting beat in the open court. That is an inexplicable defensive problem.
We known that Darby and Puckett are going to struggle on that dimension but Wells, Spears, Powell, and Wynn (while many keep saying she is a lock down defender, she gets beat routinely).
But yes, even the rangey D specialists like Wynn and Jordy still get blown by and everyone struggles getting over or under screens. That leads me to think there's a systematic problem with either design or teaching.
While we're demanding to know assistants roles, I wonder who designs defenses and teaches them. Rick Barnes always has an assistant who's whole focus is being like a defensive coordinator.