Debating about the best pitchers in baseball history is a difficult task because the game has changed so much between its different eras. However, it is very easy to compare pitchers who played during the same time period.
Some of the best pitchers in the game all were in the majors at the same time. This means that fans have gotten to see Walter Johnson face Cy Young and Pedro Martinez go toe-to-toe with Roger Clemens.
Keep in mind that a number of the players on this list had their careers overlap two eras.