Most free agent contracts are relatively easy to predict. Calculate the going rate for a single win, multiply it by the player’s projected wins above replacement over the length of the deal, and the result will come pretty close to the actual contract. This generally holds true for every type of player save one: the humble relief pitcher.

The Mets gave Luke Weaver $22 million for two years. The Tigers gave Kenley Jansen $11 million for his age-38 season. The Reds gave Emilio Pagán two years and $20 million, with the second year a player option. Run all of the reliever contracts signed this offseason through a dollars per win calculation, and they’re almost uniformly going to come out looking like terrible deals.

The sport appears to be smarter than ever, and yet teams keep shelling out gobs of guaranteed money on bullpen arms who hardly ever top 2 WAR. What’s their problem? Well, maybe teams have collectively decided to behave irrationally in one specific market, but I don’t think it’s that. I think teams are behaving as rationally in the reliever market as any other, but they happen to be using a different metric for evaluating reliever deals. The relevant metric, I think, isn’t dollars per win, but something like championship win probability added. Read the rest of this entry »

Yesterday, the Royals made a big announcement. Kauffman Stadium, long one of the most cavernous venues in the majors, is going to be a little less warehouse-like this year. The walls are moving in nine or 10 feet more or less across the board, and getting shorter by a foot and a half to boot. That’s a meaningful change for a stadium where home runs generally go to die. How massive? Time to crank up the old computer and find out.

I plugged the new dimensions from Kansas City’s press release into an equation describing a rough arc. I fit those points to a cubic spline so that it could more closely resemble the actual stadium, with its pinched-in corners. I made a few approximations as well; for instance, the wall is moving to a height of eight and a half feet “in most places,” so I just applied that across the board. I also modeled the old dimensions the same way. That way, I had two different virtual walls built to compare some batted ball data against.

Notably, my approximation isn’t a perfect replica of the stadium. I don’t have a millimeter-scale, or even a yard-scale, map of the place. I can’t account for outfielders robbing home runs, which is definitely going to be more common with the lowered walls, though still quite rare overall. But by running it through both the old and new wall dimensions, I think that this unavoidable error can be minimized. It’s pretty clear that no balls that were home runs with the old outfield parameters will suddenly not be home runs with the new ones, so the thing we’re looking for is the difference, assuming that my approximation is close enough to reality. And it is: My modeling says that over the last three years respectively, 205, 162, and 159 batted balls hit in Kansas City should have turned into homers. In reality, it’s been 186, 147, and 151. Read the rest of this entry »

Here’s a weird chart:

If you’re like me, you’re struggling to make sense of it. The value of a barrel? But aren’t barrels a measure of value themselves? That’s like asking how many dollars a ten dollar bill is worth, or how you’d rate The Lion King on a scale of one to The Lion King. But that’s not actually how it works. Barrels are defined based on exit velocity and launch angle pairs that, according to the dataset MLB used in their creation, were extremely likely to result in extra-base hits. Those cutoffs have remained the same. The results on barrels haven’t.

What gives? Well, some of it is the ball, of course. I’m not breaking new news in the long-running ball aerodynamics debate; you can read some good recent entries into tracking drag coefficients and the like here and here. Indeed, if you’re measuring barrels that way, you can see a pretty straightforward decline. Here are home runs per barrel over the years:

Read the rest of this entry »

Earlier this week, I looked into the curious case of Benjamin Button. Er, no, that’s not right. I looked into the fact that the average age of big league hitters keeps declining, like Button, while pitchers haven’t followed suit. There are any number of possible explanations for that pattern, and if the mystery appeals to you, I highly suggest reading the comments of that article, where our excellent readers have advanced a number of solid theories. I think there’s plenty of meat left on the bone in figuring out what’s causing this trend, but I won’t be delving into that (much) today. Instead, I made like Woodward and Bernstein and followed the money.

Age is a decent proxy for service time; older players have generally, though not alway, been in the league longer than younger players. Similarly, service time is a decent proxy for salary; players who have been in the league longer generally make more money than newcomers, for a variety of reasons. So is our data really just saying pitcher salaries are going up? Well, kind of.

I took salaries for all major league players starting in 2019, discarding the abbreviated 2020 season. I split them up by type – pitchers in one bucket, hitters in another, and Shohei Ohtani in both. Total pitcher and hitter salaries have both gone up – passage of time, inflation, and so on. But after a huge increase heading into 2022, when seven different hitters signed nine-figure contracts, the total outlay to hitters has leveled off. Meanwhile, pitching salaries are catching up:

As an aside, I only pulled data through 2019 because it’s outrageously difficult to get complete salary data. If you’re looking for Opening Day annualized salaries, sure, those are reported. If you’re looking for free agency contracts, again, pretty easy to find. There are no disputes about what Freddie Freeman’s salary was in 2025; it’s public record. But what about Freeman’s former teammate Justin Dean, who racked up 52 days of service time in his debut season? What about split contracts? Late debuts? Up-and-down types? I worked out a method for what I consider a very good approximation of those salaries, but I don’t feel confident going back before the start of RosterResource’s database, which begins in 2019. Even then, this is approximate, though as I mentioned, I’m confident that it’s a good approximation. Read the rest of this entry »

I have a confession to make. I started this article with a conclusion in mind, only to find that that conclusion was spectacularly untrue. But then I pivoted, and found something else I think is quite interesting. Is it obvious, in retrospect? I kind of think so. But I had fun doing it and learned something in the process, so I decided to write about it anyway.

I had a theory that the average catcher age, along with the average age for all the hardest defensive positions, had plummeted over the past decade, with the average DH age increasing as a counterbalance. My theory was that the universal DH allowed teams to massively alter their behavior. National League teams that had been playing older sluggers in the field could shift them down the defensive spectrum, either directly to DH or by displacing other old players to DH via a chain reaction of moving to easier defensive spots.

It’s beautiful logic, with just one problem: It’s untrue. Here’s the average seasonal age (as of July 1 each year) of catchers, shortstops, and DHs since 2002, the first year we have positional splits that allowed me to run this analysis:

The data is pretty noisy, which makes sense to me. It’s not like teams are targeting a given age; they’re just making baseball decisions about cost, team control, and production. Average age is a downstream result of a lot of decisions that are made for other reasons. But in the aggregate, the pattern I hoped to see just wasn’t there:

In fact, DH has experienced the greatest decline in average age across all positions. That’s very much not what I expected. I do think that some of that is overstated. First base has had the smallest decline among positions, and I’d expect many of the displaced older hitters I mentioned in my hypothesis to end up there too. But if you average the age changes of first base and DH, they’re almost exactly the league average for position players. Clearly, the data do not support my claim. Read the rest of this entry »

Back in the fall, Daniel R. Epstein of Baseball Prospectus wrote a couple of articles about where hitters stand in the batter’s box. Statcast released batting stance information last year as part of the ongoing rollout of bat tracking information that started in 2024. Understandably, the location of a hitter’s center of mass got a bit overshadowed by the wealth of information about how their bat moves through space and finds its way to the ball (or not), but Dan did his part to drag it into the light. He found a relationship between contact rate and where the batter stands. Specifically, standing deeper in the box and standing closer to home plate are both associated with higher contact rates.

Both of those findings are intuitive enough. Standing deeper in the box gives you a longer reaction time. It’s no surprise that batters who take advantage of that extra information make more contact. It’s also easy to spot a potential selection bias: The players in the back of the box are likely back there because they’re the kind of contact-oriented players who want the extra reaction time.

I saw less of a physical reason for players who stand farther from home plate to make more contact, unless they stand so far from the plate that they have trouble reaching the outside corner, but (almost) nobody actually does that. It might take your bat head slightly longer to reach the outside part of the plate, but the ideal contact point for an outside pitch is deeper anyway, so I assumed the two would balance out and chalked the difference up to selection bias. Bigger players with longer arms naturally feel more comfortable farther away from home plate, and those bigger players tend to have more powerful swings, which tend to result in more whiffs. Causation isn’t correlation, and I wasn’t ready to go so far as to assume that standing farther away from home plate actually causes a batter to make less contact. Then I watched A League of Their Own again. Read the rest of this entry »

I never pitched in Little League, but I remember many of the lessons our coach imparted to this day. Most specifically, I remember him harping on “hard in and soft away.” This was silly. Nobody on my team could throw a curveball, and even from my youthful perspective, no one could throw anything hard either. We all mostly struck out or walked; pitchers with command were pretty much untouchable in my small-town East Tennessee league. But we’re losing the plot here – as it turns out, that advice is omnipresent in baseball, from little leagues to the majors.

I’ve always been enamored with this simple and yet fascinating rule of thumb. Why does it work? Does it work, even? What’s so special about “in” and “away” relative to pitch speed? I’ve never quite found a satisfactory way to classify it. But while I was taking a look at contact point data last week, I came up with an idea for how to measure this. When you look at the data, the evidence has been there all along.

I focused on the “hard in” aspect of the adage, because major leaguers throw so many different secondaries that honing in on what “soft” meant seemed impossible. To that end, I devised a quick test to see how conventional wisdom behaves in practice. I defined “inside” and “outside” pitches by removing the middle third of the plate, then extending out nine inches past the edge of the strike zone in both directions. I looked at sinkers and four-seamers thrown in these areas to define “hard in” and “hard away.” Read the rest of this entry »

I’ve long been interested in measuring the value of making an out. Different outs count differently, and yet pretty much every baseball statistic you can imagine ignores that fact. I’m not just talking about advanced ones like wRC+ or wOBA, though those do indeed treat all outs as equal. I’m talking about basic things like batting average, on-base percentage, and slugging percentage. No one says, “Well, he batted .320, but some of those outs were in bad situations, so it was more like batting .313.” That’s not how we think about offensive statistics.

But just because we don’t count outs differently doesn’t mean that they all have the same value. This is obviously true. Striking out with a runner on third and fewer than two outs is a tragedy. Hitting a run-scoring groundout in the same situation gets the batter a long series of fist bumps back in the dugout. But when it comes to wRC+ or batting average, that distinction doesn’t show up.

There are good reasons for existing statistics to work the way that they do. Batters don’t control who’s on base and how many outs there are when they come to the plate. They don’t control whether there are fast runners on base, or whether the outfield has arms so weak that anyone could score from third base on a fly ball. In the same way that a home run is a home run is a home run, statistics that try to measure batter skill treat all outs the same. But still… I wanted to know more. Read the rest of this entry »

How much will the ABS challenge system hurt the ability of catchers to frame pitches? That question has been bouncing around my brain for quite a while now. I’d been waiting for the offseason to really dive into the numbers, and, well, we’re here. It’s the offseason. But now that I’ve dug into all the data I could find, I think the entire premise of that question might be flawed. I thought that correcting a couple of ball-strike calls a game would erase a couple of well-framed pitches. This would no doubt hurt the better framers more than it hurt the worse ones, simply because they earn more strikes and would have more to lose. At the same time, the lesser framers would have juicier pitches to challenge, boosting their numbers a bit. As a result, the gap between good and bad framers would shrink, furthering a trend that’s been going on since we first gained the ability to quantify the value of pitch framing. It would still be valuable, just not quite as valuable as it used to be. But I’m not so sure anymore. Let’s start with the data.

I pulled all the major league framing data I could. I pulled league-wide and individual catcher called strike rates both inside and outside the strike zone for the majors and for Triple-A, which in 2025 used the same challenge system we’ll see in 2026. I can tell you that 26 catchers got a significant amount of playing time in both Triple-A and the majors last season, and their called strike rate on pitches in the shadow zone in the majors fell by an average of 1.4 percentage points within the zone and 1.7 percentage points outside it relative to what it was in the minors. So while the Triple-A strike zone may be tighter, pitch framing is still harder in the majors. But the only data about how the challenge system has actually worked in the minors and in spring training of 2025 comes from MLB press releases, and it’s extremely sparse.

Of course, that data definitely exists. Baseball Savant guru Tom Tango wrote up a bunch of interesting takeaways from it on his blog a month ago. As you’d expect, players are more likely to challenge calls in higher-leverage moments, in the later innings, and on pitches that decide the outcome of an at-bat. For that reason, they tend to be less successful in those situations; they’re not challenging because they’re sure they’re right, but because they really want the call to go the other way. Tango also broke down some catchers and batters who were particularly good or bad at challenging. Not only did he provide their stats – poor Zac Veen challenged 24 pitches and got just three overturned – but Tango showed that Savant will be rolling out challenge probability numbers next year, using the distance from the edge of the strike zone to calculate the likelihood that any particular pitch will get challenged, and that any particular challenge will be successful. From there, it’s easy to calculate how much challenge value each batter or catcher creates above the average player. Read the rest of this entry »

For four years now, I’ve been updating you on the changing contours of the strike zone. By my count, this is the 10th installment in that series and the sixth specifically about the accuracy of ball-strike calls on the edges of the zone. With the implementation of the ABS challenge system in 2026, these updates will no doubt start to look a bit different. This is our last umpire accuracy update of the pre-ABS era, so let’s take stock of where we are at the end.

After a tiny dip in 2024, umpires were back on track in 2025, posting a record-high accuracy rate of 92.83% overall. In fact, 2024 was the only year in the pitch-tracking era in which umpires didn’t set a record for accuracy. However, this latest record came with a bit of controversy. Early in the season, pitchers and catchers picked up on the fact that the strike zone seemed to have shrunk. The league tightened up the standards that it used to grade umpires, reducing the size of the buffer zone around the edges of the zone. As a result, accuracy shot up specifically on pitches outside the zone, even more specifically, on pitches just above the top of the zone, causing pitchers and catchers to complain that they were losing the high strike.

This graph reminds us of a couple facts that might just be so obvious that we rarely think about them. First, the vast majority of takes come on pitches outside the strike zone. Of course they do; those are the pitches you’re not supposed to swing at. This year, for example, 68% of the calls umpires had to make came on pitches outside the strike zone. Second, it’s easier to identify balls than it is to identify strikes. Of course it is; the area outside the zone is a lot bigger than the area inside the zone. Read the rest of this entry »