Do Fewer Walks Mean More Wins?

The Minnesota Twins have issued the fewest walks of any team in baseball, despite playing in the league that features the designated hitter. There isn’t even another team within shouting distance of their 2.40 BB/9 ratio — the Phillies are next at 2.8 walks per nine — and the Twins’ strike-throwing ways are one of the main reasons they sit atop the American League Central.

Obviously, not giving out free passes is a good thing for a pitcher, but just how valuable of a skill is it? Let’s find out.

One way of measuring a single variable’s effect on an overall result is to determine the coefficient of determination. That is essentially a five-dollar phrase for “how much does Thing A cause Thing B to happen?” or, if you’re mathematically inclined, it’s the square of the correlation between two things.

This coefficient can be between 0 and 1, where zero is no relationship between two items and one is a perfect relationship (when one thing happens, so does the other, every single time), and these relationships can be either positive or negative — a negative correlation suggests that when one thing happens, the result is less
likely to occur.

So, what does this show the relationship between walks and winning percentage to be? The coefficient of determination between team BB/9 and team winning percentage since the wild-card era began is 0.21, a number that suggests that it’s not the only thing you need to win games, but it’s a pretty good thing to succeed at. In other words, it means that 21 percent of a team’s winning percentage can be explained simply by walk rate. And since 1995 (the dawn of the wild card), 57 percent of playoff teams have finished in the top 10 in all of baseball in BB/9 ratio.

While you still need to do things like score runs (as the Seattle Mariners are currently proving night in and night out), assembling a pitching staff of strike-throwers will get you well on your way to winning baseball games. Just ask the Twins.