Was it Su or was it actually Keller?

It was actually Su. Keller, for all his brilliance, could not turn a company around. After Su, AMD has been very focused and have executed around a plan (marketing insanity notwithstanding).

It's just AMD's good fortune that Intel's consistent stumbling have made their great engineering look even more outstanding in comparison.

Both were required to turn AMD around. Less competent leadership would have squandered the opportunity that Keller gave the company.

Yep, everyone deservedly gives Keller credit for K8, A4, Zen, but Su was behind the Cell, and has now shown her leadership with Zen and RDNA.