People should let go of the idea that Roger was the strongest of his era. Oda had made it clear that he was not.
Rocks, Imu and WB were stronger (maybe even Harald). Garp was his equal.
Furthermore Roger became the PK when he was heavily weakened by his sickness and after begging WB for Oden proving that the PK title is not a strength title.
Since the Oden’s flashback Oda has gone at great length to deconstruct the idea that Roger was “Top 1 ever”.