Running The Numbers on the WBC’s Extra Inning Plan

The World Baseball Classic — which starts tonight! — tweeted out a fun fact about their extra innings procedure. Your mileage may vary:

DID YOU KNOW: In extra innings, from the 13th on, teams will begin with runners on 1st & 2nd base. More fun facts at atmlb.com/12gQBbf

— 2013 WBC (@WBCBaseball) March 1, 2013

This fact’s fun factor can be debated; in a game as based in tradition as baseball, I think many would prefer as little messing with the rules as possible. But with MLB (and foreign professional leagues, most likely) worried about the health of their players, it’s in the WBC’s best interest to avoid 20-inning marathon games, as much as we may want to see them. Does their policy at least succeed in that respect?

The short answer: Yes, it should.

The problem with bases-empty extra innings — at least, in terms of producing marathon games — is roughly 70 percent of normal half-innings result in no scoring. Naturally, when the results are so tilted toward one outcome, ties are likely. Starting with runners on first and second, a wider variety of results opens up. Shutout innings are still a possibility — beware the leadoff triple play! — but the offense is presented with myriad ways of scoring runs, including many without even recording a hit or drawing a walk (a successful sacrifice bunt followed by a sacrifice fly being the most obvious).

Using Tango’s run frequency generator and the offensive statistics from the 2009 World Baseball Classic, I generated this chart of run frequencies we should expect with bases empty and with runners on first and second:

As expected, the frequency line with runners on first and second is much flatter, implying the wider variety of possible outcomes intuition suggests.

How big is the impact? I simulated 10,000 whole innings based on these run frequencies. In 5,228 of the bases empty innings, the end result was a tie (52.28 percent); just 2,119 (21.19 percent) of the innings beginning with runners on first and second resulted in a tie. Although this type of analysis doesn’t account for the change in strategy in the late innings — the home team may play for a tie in certain late inning situations — the difference here appears more than large enough to affirmatively say the WBC’s plan to avoid marathon games should work.

Is it the best option for fans? Personally, I would prefer the traditional rules, but with MLB teams and possibly other professional leagues preferring to keep their pitchers’ arms attached throughout the competition, we’ll just have to live with it.