David Pinto on Cole Hamels' brilliant performance last night:

Cole Hamels pitched eight shutout innings against the Pirates [Wednesday], walking two and striking out seven. That gives Hamels two good K/BB games in a row. Is he on his way back? He pitched a few good games in July as he appeared to work his way back, only to start August with three iffy games. In six of his last 10 games he's shown good control, so he does appear to be getting back his stuff. If Cole is on his way back, a three-some of Hamels, Happ and Lee would be very tough to beat in the post season.

Pinto knows this as well as anyone, but a pitcher's ERA will fluctuate quite a bit more than his fundamental skills. Last October, everybody was ready to anoint Hamels some sort of superhero. This was largely because he went 4-0 during the Phillies' championship run, but also because he went 14-10 with a 3.09 ERA during the regular season.
Last season, Hamels' strikeout-to-walk ratio was 3.7; this year it's 3.8. Last year, Hamels gave up 1.1 home runs per nine innings; this year he's given up 1.3 homers per nine. The only real difference between the 2008 Hamels and the 2009 Hamels is luck.

In 2008, Hamels was exceptionally lucky, giving up a .262 batting average on balls in play.

In 2009, Hamels has been unlucky (if not exceptionally so), giving up a .326 batting average on balls in play.

That's it. I sort of hate to keep hammering on this stuff because I know a lot of you have moved past ERA over the past few years. But many of you -- and more to the point, too many of the opinion-makers out there -- still believe that ERA tells you everything you need to know about how well a pitcher has pitched.

It doesn't. And Cole Hamels is your Example of the Day.