What O-Swing% Is And Why It Matters

O-Swing% – the percentage of swings at pitches outside of the strike zone – has seen a serious rise over the past thirteen seasons. In 2002, the league average of O-Swing% was 18.1%. In 2015, O-Swing% was 13.2% higher, at 31.3%. That calculates to over a 1% increase, per year, during that span, which would seem to be an unsustainable rate. To put this into perspective, Joey Votto had the lowest O-Swing% in baseball in 2015, at 19.3%. That percentage is higher than the O-Swing% league average was in 2002.

With an increase in players chasing pitches outside of the strike zone, there has been a noticeable increase in strikeouts and decrease in runs scored. In 2002, teams compiled an average of 4.62 runs per game and struck out at a rate of 6.47 times per game. Fast forward to 2015, the league average in runs scored had decreased to 4.25 runs per game and the strikeout rate per game had increased to 7.71.

Now, what does O-Swing% really tell us about a player? Let’s take a look. In 2013, seventy-five players had an O-Swing% below the league average. Of those seventy-five players, fifty-two of them had a strikeout rate below the league average and fifty-eight of them had a walk rate above the league average. Putting this into percentages, about 69.3% of all players who had an O-Swing% below the league average also had a strikeout rate below the league average. On top of this, about 77.3% of all players who had an O-Swing% below the league average also had a walk rate above the league average.

Let’s take an even a closer look at this concept. In 2014, seventy-eight players had an O-Swing% below the league average. Of those seventy eight players, fifty three of them had a strikeout rate below the league average, while fifty six of them had a walk rate above the league average. Putting this into perspective, an estimated 67.94% of all players who had an O-Swing% below the league average also had a strikeout rate below the league average. Furthermore, about 71.79% of all players in baseball who had an O-Swing% below the league average also had a walk rate above the league average.

Some people simply say they do not care if players strike out, as long as they are productive (see the 2015 Houston Astros). I am not a fan of this notion. Contact rate is a far too under-appreciated statistic. In 2014, eight of the ten postseason clubs were in the top twelve of team contact rate. On top of this, eight of the ten playoff teams in 2014 finished in the top twelve of lowest strikeout rate. The Kansas City Royals and the New York Mets, the two teams that faced off in the 2015 World Series, finished tied for first and tied for ninth in team contact rate, respectively. The Royals, the 2015 WS Champions, also finished with the lowest strikeout percentage as a team in all of baseball.

There is certainly a lot of unknown, but I think it is fair to say that not enough emphasis has been put on contact rate over the past couple of seasons. With a high percentage of players who had a O-Swing% below the league average and a strikeout rate below the league average, there is potential to connect a player’s patience with their ability to avoid striking out at high rates. If I am a general manager, I am looking at these types of players and telling myself these are the type of guys I want on my team.

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