| Player | bWAR/IP | bWAR | IP | From | To | Age | SO | ERA | FIP | ERA+ | BB/9 | SO/9 | SO/BB |
| Steve Carleton | .0183 (33rd) | 40.2 (14th) | 2196 (13th) | 1965 | 1974 | 20-29 | 1724 (7th) | 3.05 (42nd) | 2.97 (35th) | 119 (34th) | 3.22 (115th) | 7.07 (26th) | 2.20 (43rd) |
Steve Carlton accomplished quite a bit by the age of thirty. He was already a world champion, an NL Cy Young award winner, and a five-time All-Star.
His Cy Young season in 1972 deserves particularly close attention. He won the pitching triple crown that year with an insane 1.97 ERA, 27 wins, and 310 strikeouts. In 1972, Carlton became the first pitcher since the dead ball era to post a 12.0 bWAR season; a feat that would only ever again be matched by Dwight Gooden in 1985.
However, Carlton only had one other season before he turned thirty with an ERA that was twenty percent better than league average by ERA+. He also only had one more year with a bWAR above six and three full seasons with a bWAR below three.
The second act of his career would see Carlton become one of the greatest lefties in baseball history. He would make five more All-Star teams and win three more Cy Young awards after his thirtieth birthday. But for the purposes of this list, it’s hard to place him higher than tenth.