One of the reasons the St. Louis Cardinals acquired John Lackey from the Boston Red Sox in exchange for Allen Craig and Joe Kelly at the non-waiver trade deadline was Lackey's track record. The veteran was a proven innings-eater who had experienced success in October, earning a pitching "win" in the decisive games of two World Series. Plus, Lackey is a gruff character. He was as close to Chris Carpenter as the Cards were going to get (that is, if Carp was less handsome and wore a cowboy hat on occasion).
The innings-eating the Cardinals hoped to get from Lackey didn't really materialize this season. To be sure, Lackey lasted six or more innings in eight of his ten starts wearing the birds on the bat. And in one of the two starts in which Lackey failed to reach the six-inning threshold, he was ejected in the top of the third for arguing balls and strikes with the home-plate umpire. However, the Cardinals felt compelled to give Lackey a start off in the middle of September's division race because the righty was dealing with a case of dead arm. In August and September, Lackey threw 60 2/3 innings over ten starts to Kelly's 61 1/3 in ten Boston starts. So it seems fair to say that Lackey's innings-pitched total wasn't quite as high as the Cardinals had hoped it would be when they dealt for the righty.
Perhaps the low innings-pitched total for Lackey would be less important if he had pitched better while on the mound as a Cardinal. But the righty wasn't particularly sharp over his 60 2/3 St. Louis innings, posting a well-worse-than-average 4.30 ERA (120 ERA-) and 4.27 FIP (118 FIP-). So that leaves Lackey as proven postseason warrior, at least for 2014. (He is under contract for 2015 at the salary of $500K after all.)
Has Lackey pitched better in the postseason than during the regular season? The answer is yes, whether one uses the traditional measure of pitcher success, ERA, or the defense-independent FIP, which is based on only those factors a pitcher controls: strikeouts, walks, hit batsmen, and homers.
xFIP is a defense-independent stat based on strikeouts, walks, hit batsmen, and homers. Unlike FIP, however, xFIP substitutes the league-average home run rate for a pitcher's home run rate. This makes xFIP rather insightful as to how Lackey has enjoyed his postseason success relative to his regular season performance. The key to Lackey's October success? Not allowing home runs.
As you can see, Lackey has actually struck out fewer batters and walked during the half-season's worth of innings he's thrown in the postseason than when pitching in the regular season. The difference between his regular season and postseason ERA and FIP is his lower home run rate in October. The lynchpin to Lackey's postseason success has been the halving of his HR/FB rate.