By now you've heard that Randy Johnson has signed a $33 M, 2-year extension with the Arizona Diamondbacks. The contract not only makes him the highest paid pitcher in baseball history; it assures Johnson will be a D-Back until the age of 42.
It's hard to argue with the Johnson signing. He sure has been more than worthy the last couple of years. However, there's always that age bugaboo. How can a team sign a man to such a large, multi-year deal when he will be 40 before the deal even kicks in, you ask?
Well, I asked the same thing. I wondered what one's expectations should be for a 40-year-old. Maybe the salary is justified. So, I made a list of all pitchers with the records after turning 40 (i.e., in the seasons after turning 40 before July). There were 132 such pitchers (including Wade Boggs and Dave Concepcion). From that list I selected just those pitchers who started at least 35 games, about one season. I just wanted to compare Johnson to his peer group-let's assume he garners at least a season's worth of starts in his two years. There were 33 such pitchers.
It seems to me from this that those pitchers going strong at 40 continue to go strong for some time. Only a few (Carlton, Candiotti, and Hershiser) could be called poor pitchers after turning 40, and some were still very good. A few were tremendous.
It's not as if this is conclusive, but if Johnson continues to be a dominant pitcher into his forties, it won't be unprecedented.
Keep in mind that Johnson is 76 wins away from 300. He has averaged 20.25 wins a year since joining Arizona 4 years ago. When his new contract runs out, if his win average holds, he could be just 15 wins from 300. I know that this is a supposition built on a what-if, but given Johnson late start and seeming slow development, who ever imagined he would get that close?
Consider that Johnson's record stood at 88-75 after 1994, the year in which he turned 30. Johnson is 143-44 since then, good enough for 30th on the all-time list for wins after the age of 30. His projected win total over the next 3 years would put him at 205 post-30 wins, good for 5th all-time behind Cy Young (295), Phil Niekro (264), Warren Spahn (255), and Gaylord Perry (219) (and one post-30 win ahead of Sam Jones).