FanGraphs: Hamels is pitching like an ace

Philadelphia Phillies left-hander Cole Hamels put on a pitching clinic Tuesday night. In eight innings, he struck out eight Cardinals batters and walked two, allowing just one run to cross home plate. His signature changeup was in fine form: According to Pitch F/X data from BrooksBaseball.net, Hamels threw 23 of his 28 changeups for a strike, and St. Louis hitters swung and missed at 11 of those off-speed offerings.

Expect more performances like this from Hamels in the days to come. Although the 26-year-old entered Tuesday's action with a 5.06 ERA, he lowered that mark to 4.42 last night. And his peripheral stats suggest that he has been one of the best starters in the National League to this point.

In 38 2/3 innings, Hamels has whiffed 10.24 batters per nine innings, while allowing 2.79 walks per nine. Tim Lincecum, Jonathan Sanchez, Clayton Kershaw and Bud Norris are the only Senior Circuit pitchers with a higher K rate. Hamels is doing a great job of getting batters to chase his stuff off the plate, as opponents have swung at 31.6 percent of his pitches outside the strike zone. (The major league average this season is 27 percent.) That's a career-best rate, and it places him in the top 10 among NL starters.

Despite the strong peripherals, Hamels' numbers have been dragged down by abnormally high batting average on balls in play (BABIP) and home runs per fly ball figures. Hamels has suffered from a .356 BABIP in 2010, compared with a career .298 BABIP. Also obscuring his excellent pitching is a 16.7 percent home run per fly ball rate, well north of his career 11.9 percent clip and the league average, which typically sits in the 10-12 percent range. Hamels was also a bit unlucky last season, as his strikeout, walk and home run rates were virtually identical to his 2008 marks. However, his BABIP went from .270 to .325, and his ERA jumped from 3.09 to 4.32.

With fewer bloop hits falling in and fly balls finding the stands less often, Hamels should see his ERA dip this season. He currently holds a 3.31 expected fielding-independent ERA (xFIP), which gauges a pitcher's performance based on strikeouts, walks and a normal home run per fly ball rate. That places Hamels seventh among NL starters.

Roy Halladay may be the talk of the town, but Hamels gives the Phillies a second ace.

David Golebiewski is a writer for FanGraphs.