The Clustering MultiThreading (CMT) part of AMD's recent Bulldozer generation seems to have worked very nicely by itself. But the cache heirarchy of the chip was quite poor and it's not clear whether using CMT led to the cache problems they were having or not. In the end Bulldozer used CMT and performed poorly. Now, AMD have abandoned CMT in favor of the Simultaneous MultiThreading (SMT) that Intel uses in Zen and this chip looks like it's going to be performing quite well. So without more details than we're ever going to be privy to it looks like CMT was a dead end.