It's possible, but quite unlikely. I was going to compare his strikeout rate with previous pitchers who finished the season with his 11.8 K/9, but starting pitchers rarely strike out that many guys. The last qualifying starting pitcher with even an 11.0 K/9 was Kerry Wood in 2003 (11.35). The last guy to eclipse 11.8 over a full season was Randy Johnson in 2001, with a 13.41 K/9. So instead of looking at trying to find a number of direct comparisons with Greinke, let's look at MLB qualifying starting pitchers who finished in the top 5 in K/9 the last five years, along with their ERAs. 2010Tim Lincecum: 9.79 K/9, 3.43 ERA Jon Lester: 9.74 K/9, 3.25 ERA Yovani Gallardo: 9.73 K/9, 3.84 ERA Jonathan Sanchez: 9.54 K/9, 3.07 ERA Francisco Liriano: 9.44 K/9, 3.62 ERA 2009Tim Lincecum: 10.42 K/9, 2.48 ERA Justin Verlander: 10.09 K/9, 3.45 ERA Jon Lester: 9.96 K/9, 3.41 ERA Yovani Gallardo: 9.89 K/9, 3.73 ERA Javier Vasquez: 9.77 K/9, 2.87 ERA 2008Tim Lincecum: 10.51 K/9, 2.62 ERA Edinson Volquez: 9.46 K/9, 3.21 ERA A.J. Burnett: 9.39 K/9, 4.07 ERA Chad Billingsley: 9.01 K/9, 3.14 ERA CC Sabathia: 8.93 K/9, 2.70 ERA 2007Erik Bedard: 10.93 K/9, 3.16 ERA Scott Kazmir: 10.41 K/9, 3.48 ERA Jake Peavy: 9.67 K/9, 2.54 ERA Johan Santana: 9.66 K/9, 3.33 ERA A.J. Burnett: 9.56 K/9, 3.75 ERA 2006Jake Peavy: 9.56 K/9, 4.09 ERA Johan Santana: 9.44 K/9, 2.77 ERA Orlando Hernandez: 9.09 K/9, 4.66 ERA Carlos Zambrano: 8.83 K/9, 3.41 ERA Brett Myers: 8.59 K/9, 3.91 ERA That's a mean 3.36 ERA, midpoint 3.41 ERA, min 2.48, max 4.66. If Greinke finishes in the top 5 in K/9 (i.e., he keeps "striking people out" at around or at a slightly lesser clip than he is now), it would seem quite likely that his ERA would drop. How much? I dunno. ZiPS has Greinke finishing with 167.2 IP, by the way. You need 162 IP to qualify for the above lists.