MLB Single Season Leaders - Winning Percentage

1. Cliff Lee 0.880 (2008)
2. Roger Clemens 0.870 (2001)
3. Roy Oswalt 0.824 (2001)
4. Pedro Martinez 0.833 (2002)
5. Randy Johnson 0.828 (2002)
6. Barry Zito 0.821 (2002)
7. Roger Clemens 0.818 (2004)
8. Paul Abbott 0.810 (2001)
-- Chris Carpenter 0.810 (2009)
10. Chris Carpenter 0.808 (2005)
11. Brad Penny 0.800 (2007)
12. Felix Hernandez 0.792 (2009)
13. Wade Miller 0.789 (2002)
14. Curt Schilling 0.786 (2001)
15. Cliff Lee 0.783 (2005)
--- Tim Lincecum 0.783 (2008)
17. Randy Johnson 0.778 (2001)
--- Pedro Martinez 0.778 (2003)
--- Curt Schilling 0.778 (2004)
20. Jason Schmidt 0.773 (2004)
--- C.C. Sabathia 0.773 (2001)