20 Game Winners

In this summer of 2008, there are currently four pitchers in Major League Baseball with a realistic chance of winning 20 games: Brandon Webb of Arizona, Cliff Lee of Cleveland, A.J. Burnett of Toronto, and Mike Mussina of the Yankees. In 1971, Mike Cuellar, Jim Palmer, Dave McNally, and Pat Dobson each won at least 20 games. And they were all members of the same team, the Baltimore Orioles. Anyone care to calculate the odds of that happening again?