Very misleading stat. He was a starter (Not full time in 1969 WS Met team)for only mediocre teams. Mets, Angels, Astros, Rangers. I'll admit he wasn't the greatest pitcher of all time, or even his era, but for someone to even elude he was overrated is absurd.
It is a telling statistic. Lots of pitchers have been stuck on poor teams (and in the days before free agency often for their whole careers). Ryan did pitch in the post-season six times, so it is not like he was always on lousy teams. Over their careers, great pitchers have the ability to rise above the mediocrity of poor teams. Ryan didn't seem to have that ability.
I'll admit he wasn't the greatest pitcher of all time, or even his era, but for someone to even elude he was overrated is absurd.
So how do you define overrated? I believe it is when someone's reputation greatly exceeds their accomplishments.
IMO, a necessary condition for a great or elite pitcher is consistency. Ryan just lacks that. To often, Ryan would follow up a brilliant performance with a lackluster one. A Bob Gibson would follow up a brilliant performance with another good one a few days later. With Ryan, you never had that confidence.
I brought up Nolan Ryan because I have often heard his name come up in discussions with casual baseball fans. He seems to be included with the elite pitchers in the minds of these fans - a position which a careful examination of his record doesn't support. A player like Ryan can be very good and still overrated.