It is fairly easy to pick out the peak of Bob Gibson’s pitching career. From 1968 through 1970, Bob Gibson was the best pitcher on the planet. That is not even an exaggeration. He leads all players in fWAR during those seasons. He has the most or second most fWAR for pitchers every year of that time frame. In 1970 he led all players in fWAR.
Before the 1968 season, Gibson was still a highly respected and feared pitcher. He broke out in 1962 with a 6.0 fWAR season and stayed near that pace for every year after that, looking to surpass that in 1967 until his season was cut short.