Reading Joe Posnanski's blog post, Big Finish, I realized I had completely missed the Mike Mussina argument for 300 wins:
Mike Mussina just months ago WALKED AWAY from 300 victories. He has 270, and he won 20 just last year, and he retired. Is there much doubt that if he wanted to stick around he would have won 300? Coming off his 39 year, he had more wins than Gaylord Perry, than Nolan Ryan, than Phil Niekro, than Randy Johnson … and all but two pitchers with more victories (Bert Blyleven and Robin Roberts) won 300.Mussina provides an even better argument as to why someone will again win 300 games in the Major Leagues, even if he didn't quite get there himself.
1) Mussina made his Major League debut in 1991, well after the closer era began.
2) Mussina pitched in college, and made his debut at age 22, but wasn't a full-time Major Leaguer until age 23.
3) Mussina famously won 20 games just once, in his final season at age 39.
4) Mussina never made more than 36 starts in a season.
5) Mussina surpassed 240 innings in a season just twice, in 1992 and 1996, and threw more than 230 innings just one other time, in 2000.
6) During his 17 full-time seasons, Mussina threw fewer than 200 innings six times, albeit once during strike-shortened 1994.
7) Mussina pitched during the era of guaranteed contracts, and made more than $144 million in his career.
Over the final five seasons of his career, Mussina was slightly better than league average (107 ERA+), but he managed to rack up 71 wins (14 per year). Posnanski points out that Maddux posted a 104 ERA+ over his last six seasons while accumulating 82 wins, but he pitched until age 42. I think it's likely that had he wished to do so, Mussina, just completing his age 39-season when he retired, could have continued pitching for a few more seasons, accumulated 30 more wins, and been the "last" 300 game winner, either late next season or in 2011. The fact that he chose not to stick around could potentially be attributed to his career earnings, but then how do you explain Maddux ($153m), Glavine ($128m), Johnson ($167m), or Clemens ($121m)?
Mussina was an excellent pitcher for a very long time; he enjoyed very good health, and was fortunate enough to play on a large number of winning teams. If you believe those characteristics will never again manifest themselves in a Major League pitcher, by all means, consider Randy Johnson the final 300 game winner. I, however, think we are quite likely to see someone fit exactly those characteristics.