Does the Changeup Have a Strikeout Problem?

There is one pitcher out there that throws his changeup over 30% of the time and calls it a ‘heavy sinker.’ Alex Cobb aside, though, we traditionally lump the changeup in with the slider, the curve, the splitter — it’s not a fastball.

And yet, in some really important ways that go beyond movement and leak into usage, the change works like a sinker. In a league where strikeouts rule, the change actually has a strikeout problem.

We know that by movement, the change is most like the sinker. The average sinker has two more inches of horizontal movement, but the league’s changeups and sinkers have identical vertical movement. We know all about this — the beauty of the change is the difference in velocity.

Here’s the problem. In certain counts, the batter expects to see junk. Once the pitcher has two strikes on him, he goes into protect mode. Foul off the hard stuff, but look for a pitch in the 80s with movement, because that’s what the pitcher is going to throw. The percentage of fastballs a hitter sees with no strikes is 60%. The percentage of fastballs a hitter sees with two strikes is 50%.

Perhaps that anticipation with two strikes is why a great changeup alone is not enough to make for a great strikeout rate. Look at the relative correlations between a pitcher’s swinging strike rate on their changeup and their overall strikeout rates.

Minimum 100 changeups thrown, showing r and r^2 between pitch type swinging strike rate and overall strikeout rate in 2014, n ranging from 207 to 291 per pitch type.

So, while your slider’s swinging strike rate explains about 16% of the variance in your overall strikeout rate, the changeup comes in short of 10%. Quantity thrown has something to do with this, of course. The slider is thrown 13.7% of the time, the change 10.4% of the time. But since we focused only on pitchers that throw the pitch, some of that is mitigated (there are more slider throwers as well as sliders thrown). And the difference in correlations is larger than the difference in quantity thrown either way.

Is the change not a great strikeout pitch? Let’s look at the swinging strike rates on these three pitch types in two-strike counts compared to the rest of the time.

The changeup is the worst strikeout pitch among the three standard pitches, and it’s comparatively worse in those situations. In other words, while the curve and slider are both more than 60% better in two-strike situations, the changeup is only 53% better once the batter is a strike away from sitting down.

And yet, there’s virtually no difference in changeup usage by count. The change is used 10.1% of the time in one- or zero-strike counts. It’s used 9.99% of the time with two strikes. So there is still a reason to use a change, even when the batter is more prepared for the difference in speed, and relatively more likely to make contact on the pitch when he’s looking for it.

That reason is probably to get a ground ball. Here are the ground-ball rates for the main three pitch types in two-strike and non-two-strike situations.

Here, the results from the swinging strike inquiry are reversed. The changeup not only has the best ground-ball rate with two strikes, but it also enjoys the largest relative boost compared to other situations. The change gets 42% more grounders with two strikes than it does in other situations, while the curve and slider get boosts closer to 10%.

Ground balls are great, but they are only outs about 75% of the time. Strikeouts are outs 99% of the time. Perhaps, instead of asking slider pitchers about their change as they come up in the system, we should be asking changeup pitchers about their breaker.