TSMC's feature size improvements are shown by chips being released from the latest fab (and with pretty good yields, too, apparently, as AMD just released the XT series of higher clocked chips). AMD's designs are good because Zen+ was better than Zen, and Zen 2 is better than Zen+. Some of the gains may be from die shrink, but if die shrinking was all you needed to do, TSMC would license a z80, drop it on their latest process and call it a day.