Francisco Liriano and a League-Wide Trend

It’s been true for each of the last five years, that Francisco Liriano has finished each season with a higher strikeout rate than the one before it. It’s been true for each of the last four years, that Liriano has finished each season with a slower average fastball velocity than the one before it. The magnitude of these differences isn’t substantial — he’s gained a little more than 2% on his strikeout rate since 2012 and lost a little more than 2 mph — but the trends exist, and they’re headed in opposite directions.

We live in a world where older pitchers are holding their velocity better than ever before, and some are even gaining, despite what decades of convention have led us to believe. Velocity is up. Velocity is correlated with strikeouts, and strikeouts are up. Name a trait or outcome that’s positive for a pitcher — it’s probably up.

Yet clearly, something else besides velocity is working in Liriano’s favor.

Let’s take a look at a simple leaderboard, showing Zone%, or, the rate of pitches thrown inside the strike zone. It’s a leaderboard that spans a decade of qualified pitcher seasons, which is how long Baseball Info Solutions has been recording plate-discipline data. Usually, with these leaderboards, you’ll see a top five, or a top 10, but that’s not important in this case. What’s important here is two seasons, out of 943:

Lowest Zone%, qualified starters, 2005-15

  1. Francisco Liriano, 2014, 35.0%
  2. Francisco Liriano, 2015, 36.2%

In 2014, Liriano had the lowest rate of pitches thrown in the strike zone, on record. Last year, he nearly matched it. If you go by the PITCHf/x data, which is thought to be a bit more accurate, the numbers change a bit, and Liriano’s seasons drop to third and fourth, trailing only Derek Lowe from 2010-11. But the point remains: it’s a two-year run of Liriano throwing more would-be balls than anyone in a decade, and he’s not only been effective, but he’s been getting better.

The fastball is in the zone less than it’s ever been. The slider is in the zone less than it’s ever been. The changeup hasn’t much been in the zone for years. Intuitively, none of this seems overwhelmingly positive. More than anything, pitching coaches want their guys throwing strikes, and the first key to throwing strikes is putting the ball over the plate. No one is putting the ball over the plate less often than Liriano, yet the strikeouts keep piling up. How could this be?

It’s not this simple — it never is — but let’s split Liriano’s career into two parts, before joining the Pirates and after joining Pirates, and observe one more plate-discipline statistic: O-Swing%, or, the rate of pitches thrown outside the strike zone which generate a swing from the batter.

Francisco Liriano, O-Swing%

  • Pre-Pirates: 29.9%
  • Post-Pirates: 34.1%

However counter-intuitive Liriano throwing fewer strikes and becoming more effective is, this is even more so. As Liriano has become the most extreme ball-thrower in the history of plate-discipline data, batters have actually been chasing more at his increased offerings outside the strike zone. Liriano’s O-Swing% wasn’t the highest in baseball last season, but it was in the top 15, which is shocking, given how rare it is that he works within the strike zone. As Liriano throws fewer and fewer pitches over the plate, you’d think the league would begin to adjust, and simply let Liriano beat himself with balls leading to walks. However, the league’s inability to lay off these unhittable offerings outside the zone (or make contact with them — Liriano was tied with Clayton Kershaw for baseball’s lowest O-Contact% last season) has given Liriano no incentive to start putting anything over the plate.

Even Bryce Harper, the National League’s Most Valuable Player and baseball’s best hitter since steroid-era Barry Bonds, couldn’t help but chase Liriano’s looping slider:

But Harper’s not alone, and neither is Liriano. This is happening all across baseball; Liriano’s just the most extreme example.

League-wide Changes in Zone% and O-Swing%
Season IP Zone% O-Swing%
2008 43357.2 50.3% 28.0%
2009 43272.0 50.4% 27.9%
2010 43305.1 50.4% 28.4%
2011 43527.1 50.1% 28.9%
2012 43355.1 49.5% 29.3%
2013 43653.1 49.2% 29.7%
2014 43613.2 48.8% 30.1%
2015 43407.2 47.8% 30.9%

Every year since 2010, pitchers have been throwing fewer and fewer pitches in the strike zone, and not only that, but hitters have been swinging at higher and higher rates of those pitches outside the zone. Last year, we saw the most substantial one-year changes on record, with Zone% dropping by a full percentage point and O-Swing% increasing by nearly the same amount. A 1% drop in zone rate may seem inconsequential on the surface, but consider that hundreds of thousands of pitches are thrown in a single baseball season. Even 1% means that there were thousands fewer pitches thrown inside the zone than ever before. Tens of thousands from just five years ago. The ever-increasing velocity across the league gets much of the credit for baseball’s already-historic and rising strikeout rates, but this is perhaps an understated aspect.

Of course, it’s entirely possible, and maybe even probable, that this could be the result of increased velocity. The majority of swings at pitches outside the strike zone come against breaking and offspeed pitches, but it seems reasonable that with batters having to be geared up for the fastest fastballs the game has ever seen, that they’re less able to identify and react to breaking pitches outside of the zone. Baseball was already a game of milliseconds, and the time that a batter has to decide whether to swing is shrinking by the day.

Another explanation to consider is that the called strike zone is larger than it’s ever been, and so not only do pitchers have more incentive to work around the zone, but hitters could be feeling more pressure to protect themselves by swinging at these pitches.

Just last season, in addition to Liriano’s unprecedented work outside the strike zone, Carlos Carrasco posted the highest O-Swing% on record in the PITCHf/x era. Jacob deGrom, Kyle Gibson, Corey Kluber, Max Scherzer and Madison Bumgarner all stand in the top-20. That’s six of the highest 20 O-Swing rates in the last eight years — spanning 686 qualified seasons — all coming in one season. The Zone% leaderboard is even more extreme, with nine of the bottom-20 — Liriano, Gibson, Dallas Keuchel, Wade Miley, James Shields, Tyson Ross, Jeff Locke, Jon Lester, and Gio Gonzalez — concurring last season.

Hitters simply don’t seem to be adjusting, and as long as that’s the case, pitchers will continue giving them fewer and fewer pitches inside the zone to hit, with strikeouts continuing to pile up. Liriano is the posterchild of this approach, but plenty of other pitchers across the league are beginning to follow suit. It’s a pitcher’s world we’re living in, these days. Hitters have found themselves on the outside, looking in.

August used to cover the Indians for MLB and, but now he's here and thinks writing these in the third person is weird. So you can reach me on Twitter @AugustFG_ or e-mail at

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6 years ago

Kyle Gibson?

6 years ago
Reply to  cwsoxfan

There are some really weird names on the list… Gibson, Ricky Nolasco, Aaron Harang, Carl Pavano. I think I’m looking at the right list…