Tom Seaver spent twenty years pitching in Major League Baseball for the New York Mets, Cincinnati Reds, and toward the end of his career, the Chicago White Sox and the Boston Red Sox. He is, without question, one of the top ten pitchers in baseball history, and a strong case can be made for him as the greatest pitcher of all time.
Born George Thomas Seaver in Fresno, CA on November 17, 1944, Seaver made his major-league debut with the Mets at the age of 22, early in the 1967 season. That year, the Mets were beginning to assemble the starting rotation that would lead to their first World Championship. Seaver won the National League Rookie of the Year award that season, throwing 250 innings with a 2.76 ERA and a winning record for a Mets squad that assembled a 61-101 overall record on their way to a 10th-place finish in the league. The next year, the Mets added Nolan Ryan and Jerry Koosman to their staff, and they improved to a near-.500 record. In 1969, the Mets' season is well-documented, and Seaver was an integral part of their championship season, throwing over 270 innings with a 2.21 ERA, 60 percent better than the league average. Based on that and his strong won-lost record of 25-7, he won the first of his three Cy Young awards. Seaver's twenty-year career was marked by his durability and excellent pitching for the first eleven years (mostly with the Mets, including a half-season with Cincinnati in 1977), followed by nine more years as an above-average, but not great, pitcher. He had some truly bad seasons late in his career, in particular in 1983, when he only threw 111 innings with a 5.50 ERA for the Reds. He came back from that campaign to post solidly above-average seasons for the remainder of his career. Seaver is a member of the Hall of Fame.
Seaver was an intelligent pitcher, and like Ted Williams did for hitting, he wrote the book on the subject--quite literally. The Art of Pitching explains how to use all of the basic pitches effectively, how to throw them correctly, and discusses Seaver's conditioning program and mechanics. Mechanically, Seaver can best be compared to the younger version of Roger Clemens, before Clemens started to have groin and leg troubles; the canonical example of a right-handed "drive-and-drop" pitcher is Seaver. In terms of his pitching philosophy, Seaver can be better likened to Greg Maddux or Pedro Martinez. He disliked allowing walks, and his high workload in innings was not just a result of conditioning and good mechanics, but also efficiency in retiring batters.
Any case for Seaver as the best pitcher in history must rely on a cross-era comparison to dead-ball era pitchers. Walter Johnson is almost certainly the best pitcher from that era, based on the combination of his level of performance (high) and the length of his career (amazingly long). Seaver holds similar credentials for the post-1968 era. His career does not have the same peak level of performance as some of his contemporaries, such as Steve Carlton and Jim Palmer, but his longevity and consistency of performance compares favorably to Johnson (relative to his contemporaries). Ultimately, neither the statistics nor the scouts can give an overwhelming case for nominating either man over the other as the greatest pitcher in history.
Credit goes out to baseball-reference.com for the stats. As always, /msg WRW with additions or corrections. I'd like to get mechanical comarisons from someone who got to see Seaver pitch, as opposed to reading his lectures on proper mechanics. Likewise, if you have input on the Johnson/Seaver debate, /msg me with your thoughts.