Seven Trends That Defined the “First Half”

In one sense, we are halfway through the season. In another sense, though, we are not — we are 59.5% of the way through the season, if you count up all the games played. Regardless! There’s no baseball today, so what better time to take stock of the general state of the sport?

To that end, I’ve identified seven trends that have defined the 2025 season to this point. In no particular order:

Changeups are going wild

You may have heard at some point that this was the year of the kick change. All through March and April, local and national writers alike regaled the baseball reading audience with stories of this mythical new pitch, destined to revolutionize pitching as we know it.

So has it? Mostly, no. By run value and whiff rate, changeups are performing roughly as well as they have over the last few years. But the changeup itself is clearly changing.

To be fair, it’s unclear whether it is specifically the growth of the kick change that is driving these numbers. But there’s no question that the changeup, as a pitch type, is getting kickier. In 2021 — just four seasons ago — the average changeup was thrown with seven inches of induced vertical break. That’s dropped all the way to 4.4 inches this season, including nearly one inch more drop from 2024 to 2025. That’s a staggering amount of change considering these figures are aggregated at the league level.

These depth-y changeups are defining some of the more notable pitcher campaigns. Merrill Kelly, Cristopher Sánchez, and Kris Bubic — to name three guys — are putting together career years riding their negative induced vertical break changeups as far as they can take them.

Four-seam fastballs are still going out of style

Much was made last season of the Red Sox throwing the fewest four-seamers in the history of the sport. While they took it to the extreme, Boston was merely the poster child of a broader league-wide trend — last season featured the fewest four-seamers of any season on record. The thinking behind fewer fastballs is pretty straightforward: A pitch that goes straight is easier to hit than one that bends. Hitters, as a result, tend to perform better on the pitch than they do against breaking balls, like sliders or curveballs, or offspeed pitches, like changeups and splitters.

At the time, Red Sox pitching coach Andrew Bailey gave a quote about four-seamers that circulated widely among the pitching internet.

“We speak a lot about the fastball in general being a jab and equating that to boxing,” Bailey told Jen McCaffrey of The Athletic. “If you’re going 12 rounds or eight rounds, you’re not going to win by throwing jabs the whole time. The damage is done by throwing your haymakers in your best sequences. Jabs need to be located supremely to do any damage.”

In 2025, the “fastball as jab” philosophy seems to be truer than ever. Pitchers are throwing even fewer four-seamers in 2025 than they did in 2024. Probably not coincidentally, the pitch remains as effective as it’s ever been, at least by Statcast’s context-neutral run value statistic. Last season was the first time in the Statcast era that four-seamers had a positive run value (so, good for pitchers.) It has dropped a little this season, but isn’t far off that 2024 mark. (The previous record was -0.16 runs per 100 pitches; in 2025, it’s at -0.02 runs per 100 pitches.)

It seems like offense should be improving…

By a handful of key metrics, it looks like hitters are finally gaining an edge over their foes on the mound. Exit velocities are higher than ever. Hard-hit rate is up, jumping nearly two percentage points from 2024 to 2025. Barrels are as frequent as they’ve been at any point this decade. And all of these gains in batted ball quality are coming without a contact tradeoff. In fact, strikeouts are actually down this season, while walks are up, perhaps as a result of the smaller strike zone. So surely offense is way up?

…But it isn’t

The league-wide OPS in 2024 was .711. In 2025, it’s all the way up to… .715. So what’s the deal? There are a couple potential explanations.

One is that — shocker — the ball is different. Drag is up. According to a June report from The Athletic, the drag coefficient — .3514 — is higher than it’s been at any point in the Statcast era. Higher drag means that the ball won’t carry as far. The Athletic report speculates that the seams are higher, but the “why” is less clear, beyond it being a function of the ball-to-ball variation caused by the hand-stitched nature of the seams. Whatever the reason, the numbers are the numbers: Drag is up, which is making hard-hit balls less impactful.

The other theory I’ll throw out comes courtesy of a Russell Carleton Baseball Prospectus story from last month. As Russell reported, outfielders are catching so many fly balls now. Why? His theory is multifaceted, but in short, it’s that they’re getting better at everything — chasing balls down, running fast, positioning themselves. Russell concludes that it isn’t that the parks are getting smaller or that more lazy fly balls are getting hit; it’s that the defenders themselves are improving. The always-improving outfielders are almost certainly putting a dent in league-wide offense.

Those are my two best guesses. But if I’m missing anything, I’d love to hear your theories, because otherwise, I’m stumped.

Arm angles are dropping

Meanwhile, pitchers continue to plot the demise of the guys holding the bats. Each year, arm angles are dropping further. The reasons why are clear enough — lower arm angles allow for flatter approach angles, which are increasingly prized by smart organizations, and might lead to fewer injuries.

Matthew Trueblood of Baseball Prospectus wrote about the arm angle revolution in April. He bucketed pitchers by arm slot and analyzed the performance of fastballs thrown by those buckets to the upper-third of the strike zone. Unsurprisingly, he found that the lowest arm angle pitchers have the best batted ball outcomes and the highest whiff rates. As the arm angle climbs, the outcomes decline.

Pitch mixes are expanding

As pitchers lower their arm slots each year, optimizing the performance of their fastballs and potentially even keeping their arms healthier, they also add more pitches. All the way back in February, Lance Brozdowski forecasted that this would be the year of the pitch mix.

Lance noted that, after a few seasons of roughly no change, pitchers have thrown more types of pitches each season since the 2022 campaign. Using the parameters of a minimum of 2,000 pitches thrown and 100 pitches per pitch type to qualify, he found that the average number of separate pitches per starting pitcher was 4.3 in 2022. In 2024, it was 4.7; Lance predicted it would eclipse five in the 2025 campaign.

We’re not quite there, but we are very close. Using similar parameters — 1,000 pitches thrown and 50 total pitches per pitch type because the season is (roughly) halfway done — I found that pitchers are averaging 4.93 separate pitches thrown, which would be the biggest jump on record. No longer is the new hot thing “throw your best pitch more” — pitchers are realizing that adding ever more pitches is the way to go.

Third base coaches still aren’t aggressive enough

In March, Patrick Dubuque wrote one of my favorite pieces of the year. Revisiting some Russell Carleton research from 2010 titled “Why All Third-Base Coaches Should Be Fired,” Patrick found that — even in the 15 years since Russell wrote his original piece — the success rate in sacrifice fly situations remains unreasonably high. In 2010, Russell found that the success rate was 96%. In 2024, Patrick found it was 97%. Breaking the data down further, he found that there are a significant number of fly balls hit between 250 and 300 feet where third base coaches tend to hold runners, despite the extremely high success rate on balls hit to this region.

Referencing Patrick’s piece, Ben Lindbergh, in Effectively Wild’s preseason bold predictions draft, guessed that the sacrifice fly success rate would fall below 94%.

No dice. Through the first 59% of the season, the sac fly rate is actually even higher than it was in 2024. Using Baseball Savant, I found 778 successful sacrifice flies, and 18 double plays where a runner was thrown out at home. That’s a 97.8% success rate, if my methodology was correct there. Time to get bold, third base coaches! You’ve got (almost) nothing to lose! (Unless you’re Matt Tuiasosopo.)