For a program like Memphis, the Penny move makes sense. But there's a huge difference between running an AAU program and coaching a major college basketball program. College coaches are machines, and the attention to detail is at a level most of the public has no conception of. Penny will win some games rolling the ball out against inferior competition, but he's going to get beat by a lot of experienced coaches. He's not Calipari.
Stackhouse has been in NBA coaching circles for awhile now. He will be a better coach, but he won't have the support that Penny gets in Memphis. If anyone has ever listened to Gary Parrish of CBS, you know that they live in a weird little bubble where Memphis basketball is a blue blood.