Most perfect-game pitchers are exceptional players. Only one or two caught lightning in a jar. Modern era perfect game pitchers (not including Harvey Haddix, as MLB does not consider the greatest game ever pitched to be a perfect game):
Don Larsen: average at best.
Jim Bunning: HOF
Sandy Koufax: HOF
Catfish Hunter: HOF
Len Barker: average at best
Mike Witt: above-average MLB pitcher
Tom Browning: above-average MLB pitcher
Dennis Martínez: Almost-elite level MLB starter.
Kenny Rogers: Outstanding for several years, above-average career.
David Wells: Outstanding for several years, above-average career.
David Cone: Outstanding for several years, above-average career.
Randy Johnson: HOF
Mark Buehrle: Borderline HOF, outstanding MLB pitcher.
Dallas Braden: Injuries, small sample size
Roy Halladay: Probable HOF
Philip Humber: Total outlier, flash in the pan.
Matt Cain: Outstanding for several years, above-average career.
Félix Hernández: Elite pitcher in his prime.