Nobody improves on this team with current coach. Tatum and Brown improved after summer with team USA coached by Popovich. But look at the rest they don't ever improve. Robert Williams three years later the same player. Has no idea. Semi. Same bad player. Javonte same. Carsen Edwards worse. Grant Williams still can't shoot. Smart still doesn't know when to shoot. Is there one player that has progressed?
Isaiah Thomas, Marcus Smart, Avery Bradley, Jae Crowder, Kelly Olynyk, Evan Turner, Terry Rozier, Tyler Zeller, Aron Baynes, Marcus Morris and Daniel Theis would all like a word with you. All have improved under Brad Stevens.
Established All-Stars in Kyrie and Horford also had career-best years under him. Further, to attribute Tatum and Brown's growth to playing on a terribly woeful Team USA squad is ridiculous.