Count Got Your Tongue? Consider the Breaking Ball

Falling behind in the count puts an enormous amount of pressure on the pitcher. It’s in his best interest to throw a strike and retake control, but knowing this, hitters are more likely to swing. Aiming outside the zone is dicey: It’s great if the hitter bites but disastrous if he doesn’t, and the risk generally outweighs the reward. A pitcher would ideally execute a borderline strike that hitters can’t help but pass up, but that’s easier said than done. Navigating this situation is tricky, and just from a numbers perspective, whoever’s on the mound is pretty much always in trouble. The question isn’t “can the pitcher emerge victorious,” but rather, “Can he escape with minimal harm?”

For decades, pitchers have relied on their fastballs to fight these uphill battles. Part of that is because long ago, some of them actually believed throwing a slider or another secondary pitch wasn’t very manly. You ain’t tough unless you blow a 2–0 heater by your opponent, I guess. But really, it’s because a fastball is the pitch a majority of pitchers are comfortable with, and it’s the one they can most reliably lob in for a strike. If your goal is to equalize the count, why risk using an erratically moving curveball to achieve it?

Unfortunately for those old-timey hurlers, they’re probably rolling in their graves at the apparent cowardice of modern pitchers. Rather than adhere to axioms, pitchers today are challenging notions of what’s “right” or “wrong” in pitching, aided by advancements in pitch- and body-tracking technology. One example of such sacrilege is the continuously increasing rate of breaking balls — sliders, curveballs, and the like — thrown in disadvantageous counts:

It’s true that breaking ball usage is up no matter the count or situation, but I find it particularly interesting that the trend remains strong even when pitchers fall behind. The name of the game is optimization. If teams didn’t think opting for breaking balls when behind in the count granted them an advantage, we wouldn’t see this happening. Granted, just because teams do something doesn’t necessarily means it’s effective, but a league-wide jump of eight percentage points in pitch usage is significant and worthy of investigation.

One thing that’s undeniably true? Fastballs are easier to land for strikes, plain and simple:

Nothing much to add here. The raw disparity in zone rate when behind in the count isn’t huge, but considering that throwing a ball in these situations costs the pitcher 135 points of wOBA on average, it’s a big deal. Add that increment in wOBA to a lackluster hitter, and he’s suddenly an All-Star. On the surface, there’s nothing apocryphal about fastball-centric gospels. (They are, however, misleading. But more on that later.)

Maybe breaking balls are becoming more prevalent because they offer another advantage: minimizing damage on contact. Just like how the average pitcher is better at locating a fastball than he is a breaking ball, the average hitter is better at attacking a sinker than he is a slider. But if we look at the numbers, the difference between the two pitch types in terms of wOBAcon — that’s wOBA on contact — is trivial (again, only when behind in the count):

Based on what we have so far, there’s a clear best option. If you know hitters are going to perform similarly well on contact, you might as well go for the pitch that will more likely even the count. And it seems a bit confusing that an increasing number of pitchers are opting for… not that. Time to put on our tin foil hats: Advocates for breaking ball reliance must be peddlers of weighted balls and other frivolous athlete junk!

Well, no; we’re missing crucial variables that have been purposefully omitted for a stronger rhetorical punch. The allure of the behind-in-the-count breaking ball isn’t found in zone rates, nor is it related to wOBA on contact. Instead, it can be found in the table below, which shows the percentage distribution of the possible outcomes against a given pitch:

Breaking balls induce passivity. Hitters are less likely to swing against them, and even when they do commit, they’re more likely to come up empty. That’s probably because big league hitters, accustomed to baseball convention, still expect a fastball when the count turns in their favor, and a looping curveball catches them off-guard. If they do recognize the spin, they probably also know better than to chase after it. A pitcher with solid breaking ball command, then, can easily gain the upper hand, knowing that a well-executed breaker maximizes their chances of landing on a safe outcome.

But there remains a trade-off. Exceptions exist, but in general, a pitcher’s fastball command is greater than or equal to his breaking ball command, which means the fastball still provides an advantage in zone rate. What’s more valuable: Seven percentage points of zone rate, or five-to-six percentage points of whiff rate and batter take rate? The answer, as it usually does, depends on the individual pitcher and who he’s facing off against, but let’s look at the general idea. Assuming league-average conditions and with the help of some not-very-rigorous math, we can arrive at a fair estimate of what the answer might be.

You know how baseball works: The pitcher throws either a strike or a ball, which the hitter puts in play, whiffs at, fouls off, or takes. That generates eight distinct outcomes. For each outcome, using league-wide data in hitter-friendly counts, I worked out the wOBA incurred by the pitcher. An example: When behind in the count, pitchers throw a fastball for a strike 58.6% of the time, which hitters put into play 18.3% of the time for a .413 wOBA. Multiply everything, and we get -0.044, or a “cost” of 44 points of wOBA, the sign flipped to reflect the pitcher’s perspective. The process is repeated for each outcome. Adding them all together produces an expected value: a weighted average of the outcomes possible in an isolated pitcher-batter matchup. Here’s the full matrix for fastballs only:

Followed by the breaking balls:

Notice how both final sums are negative. As mentioned earlier, the goal of navigating a disadvantageous count isn’t to win but rather lose less. And according to our calculations, it’s the breaking ball that best supports this cause. The key takeaway is that a decrease in zone rate is offset by an increase in called strike rate. While pitchers incur more harm from a taken breaking ball outside the zone than a taken fastball outside the zone (not because one is inherently worse, but because of the probabilities), eight points of wOBA isn’t a dealbreaker. It also turns out that preventing hitters from putting in-zone pitches in play makes a noticeable difference: 16 points of wOBA, to be exact. Breaking pitches have already broke even at this point, and they pick up a small edge in whiffs on both strikes and balls as well. The only area where fastballs have a pronounced edge is in the foul ball department, but it’s not enough to make up for their shortcomings elsewhere.

All this is a generalization, but the point stands. After factoring in all the outcomes and the expected gains or losses in wOBA, it clear why popping in a 2–1 curveball is becoming less of a novelty and more of a strategy. Simply citing the reliability of a fastball isn’t enough, because pitchers aren’t just facing lifeless targets. They need to retire actual big league hitters, for whom squaring up a behind-the-count fastball is about as routine as it gets. So far, though, they still seem thrown off by an unexpected breaking ball, and it’s a tendency more pitchers can (and should!) exploit. Relying on a slider when behind may not work out in the short-term, but consistently doing so would eventually yield better results — assuming they’re facing more or less average hitters, that is.

I won’t go into how greater breaking ball usage could potentially aggravate the shoulder or create imbalance within a pitching repertoire. That’s beyond the scope of a single article. This is just some of the fundamental logic behind what’s been called “pitching backward,” supported by basic but meaningful arithmetic. Sorry, Old Hoss Radbourn; as long as you remain incensed (I assume) at the current state of pitching, you’ll probably be tossing and turning for decades to come. But hey, if you decide to haunt the living out of frustration, feel free to let us know.