During the long, cold off-season, a tiny morsel of info leaked out from the Orioles front office. Turns out some tall foreheads in the O’s analytics department pounded their keyboards to the bone to learn that there is a “magic number” as it relates to winning ball games: 39 batters faced. If, when pitching at home, a team can keep the total plate appearances of their opponents under 39, they stand a great chance to win.
In the interests of due diligence, let’s check in on this phenomenon as we near the end of May. Does the 38 batters faced threshold still make the difference between winning and losing? Spoiler: of course it does!
Using the trusty Play Index, we can track which teams played the most games in which they allowed the opponents to come to the plate 38 times or fewer. Would you believe it? When they do this, they win! The left is games with 38 and below, the right is 39 and above.
It is slightly amazing to me that the Braves have a winning record in these games, though their terrific run prevention limits the number of games in which they get to the 39 threshold. Conversely, the bad teams with bad pitching staffs are constantly pushing past this limit and losing many games because of it. Bad offenses have a harder time squeaking out wins even when the pitching plays along. The Blue Jays are cursed/just plain bad.
Less stunning: no team has a losing record when holding their opposition under 39 batters faced. Even the Astros were not able to lose games in which they received decent starting pitching. League-wide, teams have a 299-103 record when holding opponents to 38 PAs and below. When they go over? 78-210.
I don’t exactly know why but this entire concept fascinates me. It isn’t a hard and fast rule, as the Braves record when allowing 39 batters faced and above shows. But just as keeping batters faced below 39 correlates nicely with winning, so does scoring a tonne of runs. The Braves averaged six runs per game in this five-game sample. Teams that score six runs are 402-67 in 2013. It’s all related. Fewer base runners means fewer runs, even in this homer-happy day-and-age.
Interestingly, if you take this to the individual level, it works as a beefed-up version of WHIP. Creating a total batters faced per nine innings column doesn’t follow the WHIP leaderboard directly, though Matt Harvey, Clayton Kershaw and Hisashi Iwakuma lead the way in both. Iwakuma and Harvey both face just 34 batters per nine innings pitched, which seems like a pretty terrific way to win baseball games to me. Poor James Shields deserves better than his Royals lot in life. But you and I already knew this.