Bob Gibson is without a doubt one of the most talented pitchers to grace the sport, his fastball was ethereal and his pacing methodology revolutionary. Throughout Gibson's career he relied heavily on his fastball, and so it comes as no surprise that his Achilles' heel would be the round tripper, giving up nearly 17 per season, although not Robin Roberts' levels - 26 per season for 19 years - but a trend that impacted the right hander none the less.
Something funny happened to his homerun rates from 1966 on, one could argue he was finally entering his prime at age 30, and that he'd had prior success, which is true, seasons of ERAs hovering slightly above and below 3 seemed to be the norm for Gibson in a very hitter friendly ballpark. In May of 1966 the Cardinals moved into Busch Stadium II - a pitcher's park - and Gibson would see his homerun rates drop dramatically meaning less runs meaning a lower ERA, including a season with a sub-2 ERA, simply amazing.
There isn't a question of whether Gibson benefited from changing parks - he did - but consider it a evening out of sorts, going from hitters' to pitchers' parks Gibson still maintained his high level of play while reaping the goods of different stadiums suited for opposite aspects of the game. I'm not going to be one to question Gibson's accomplishments or call his great seasons frauds because of his ballpark; instead I question how good would he have been if for the longevity of his career he would've had a stadium like PETCO Park positioned behind him along with seven worthy fielders?
Thanks to the wonderful world of park and league adjusted statistics we can question and give a somewhat accurate answer of questions like this and how many homeruns Babe Ruth would've hit playing in Coors Field. The process for pitchers involves figuring out the park factor - thank you Baseball-reference.com - and going from there you can easily convert and compare statistics. In this case the 1968 version of Dodgers' Stadium compares nicely to PETCO (Dodger Stadium boasted a 92 pitch rating, PETCO 91) giving us a pre-programmed reference to use in this inquiry.
Before we dig into the projections, remember that Jake Peavy allowed 33 homeruns in 2003 while pitching at Qualcomm Stadium, a season later the San Diego Padres' began playing at PETCO and his homerun rate reached 31 for the next two seasons combined. In fact the highest he's allowed was 23 in 2006, clearly the ballpark was a huge help and there's even a correlation with his strikeout rates. Peavy is a very good pitcher but nowhere close to Gibson - not yet at least - consider it a prime example of how a supreme talent with a noticeable weakness can be matched perfectly with a ballpark as a modifier.
Bob Gibson's Career Numbers
Bob Gibson's Projected Numbers
In the projection Gibson gives up an average of 13 homeruns per season, four less than his real life average and only once does he approach his legit career high in homeruns allowed. Let's see the actual changes in each major statistical category if Gibson had been a Dodger in the 60's or a modern day Padre:
Comparison of Stats
To put it simply: Gibson would've been the best statistical pitcher ever if he played in Dodgers Stadium - Gibson, Koufax, and Drysdale, man that would've been a rotation for the ages - and would've had similar stats in PETCO, and that's without even considering the amount of run support Gibson would've received