By the time Jason Marquis took the mound for the second inning on Sunday, he had a six-run lead to play with against the Florida Marlins. That was in part because of an offense that hustled its way into a few runs in the early part of the first inning. But the biggest reason Marquis had a comfortable lead – and one of the main reasons the Nationals had done enough to beat the Marlins by the end of the first inning – was the pitcher himself.
His at-bat in the bottom of the first was a display of savvy hitting; he took two breaking balls from Javier Vazquez, knowing he'd get a fastball on the third pitch of his at-bat. And when Vazquez left it up in the zone, Marquis slapped it down the left field line against an outfield shifted well away from it. The double scored two runs, and though Marquis was thrown out trying to advance to third, the inning ended with Washington up 6-0.
Although NL pitchers don't bat a lot, they do bat a couple of times per start, and their at bats count. A pitcher who can swing the bat, like Marquis or Liván Hernández, can add as much as half a win per season. WAR statistics—that is, "wins above replacement"—purport to be comprehensive measures of player value and should capture pitcher batting. While both fangraphs and baseball-reference sites show WAR for pitcher batting, there are problems with these data that render them less useful than they should be.
At fangraphs, the issue seems to be computational. Batting WAR for pitchers is not centered at zero, so pitchers who hit better than the average pitcher still have negative WAR. At this point in the 2011 season, only 10 pitchers have positive fWAR (led by J.A. Happ at 0.3), whereas 71 have negative fWAR. The total pitcher batting fWAR for the league is –14.0, or about a win per team. Conceptually, I think this should be zero—an NL pitcher is helping his team with the bat if he hits better than his average opposing pitcher. I don't see how the fWAR numbers can be meaningfully interpreted—if they are added to the pitcher's pitching WAR, NL pitchers would be at a big disadvantage to AL pitchers.
Fortunately, the other site, baseball-reference, seems to have pitching batting rWAR correctly centered around zero. My complaint there is that most table and leaderboards show pitching rWAR and a pitcher's batting rWAR separately, without showing their sum, so batting WAR is often overlooked. For some uses of rWAR, this is a serious omission.
For example, if you just look at pitching rWAR, Walter Johnson (127.7) is third on the career leaderboard, behind Cy Young and Roger Clemens. But if you add in their batting rWAR, Johnson—an excellent hitter—moves up to 139.8, easily surpassing Clemens and nearly catching up with Young.
Pitcher batting should be routinely included in measures of pitcher value. The measure that excludes pitcher batting should be a supplementary measure, not the main measure.