Having taken advantage of a recent Yankees slump, the Red Sox are tied for first in the American League East. Though one of the big conversations about the team was how it would respond to losing David Ortiz, the Sox so far have also gotten very little from David Price. They’ve gotten nothing from would-be shutdown relievers Carson Smith and Tyler Thornburg. On the pitching and health side, things have gone anything but smoothly, and yet the Red Sox are fifth-best in runs allowed per game. By overall pitching WAR, they’re fourth. Their rotation ranks fourth, and their bullpen ranks fifth. The Red Sox have had one of the more effective pitching staffs in major league baseball.

Of course, so much is about the personnel. The Sox have seen the very best of Chris Sale, and they’ve also seen the very best of Craig Kimbrel. It’s not easy to find a better starting pitcher, or a better option to close a game down. But we can talk at least a little about team strategy. It’s not something we talk about often, but pitching staffs can and do have tactics, and the Red Sox are aiming their fastballs higher than anyone.

Why does that matter? Well, I already told you how the Red Sox have pitched, overall. But we can break things down further by isolating how the fastballs have done, themselves. According to Baseball Savant, Red Sox pitchers have allowed baseball’s lowest wOBA on fastballs. Folding in Statcast information, they’ve allowed baseball’s second-lowest expected wOBA on fastballs. Looking at the numbers right here, the Red Sox rank first in baseball in fastball run value. The Sox have pitched well, and they’ve pitched off their heaters.

And those heaters, combined, have been very unusual. You already know how, because of the headline. Before getting into that, here’s some league context. Baseball Savant recently added some new search features, allowing you to search by average pitch location. In this plot, you can see the league-average fastball heights, over the past decade. This is expressed in feet, and the middle of the strike zone is usually right around 2.5.

Recently, we’ve seen a very modest rebound. Fastballs achieved their lowest average height in 2015. Since then, the average height has gone back up a little bit, although it’s still shy of where it was even a few years ago. This is something we’ve discussed before, as hitters are getting better and better at taking the low pitch deep. There’s possible value to be gained by attacking fly-ball hitters up. The league is slow to adjust to the adjustment, but baseball does very few things all of a sudden.

Anyway, that shows the league trend, as a whole. Now we can focus on 2017, and break things down on a team-by-team basis. Here are every team’s average fastball heights:

The Orioles are throwing baseball’s lowest fastballs. On average, their heaters have crossed the plate 2.34 feet above the ground. That’s only barely lower than the Rangers and Astros. But your attention is probably most drawn to the team at the extreme left. The Red Sox are throwing baseball’s highest fastballs. On average, their heaters have crossed the plate 2.84 feet above the ground, which means the gap between the Sox and the Orioles is an even six inches. The Sox are separated from the second-place Rays here by a decent margin, and the Sox also have the largest such increase compared to last year:

I switched the units here from feet to inches just because the numbers otherwise look pretty small. Even last season, the Red Sox, as a staff, threw baseball’s second-highest fastballs, but now they’ve gone up another 1.8 inches. There’s presumably something to be written about the Astros, down at the other end, but that’s something for another day. The Red Sox threw high, and now they throw more high. They’ve done the very opposite of regress to the mean.

It isn’t just a matter of adding different pitchers. Many of the Red Sox pitchers are just throwing their fastballs higher than they used to. There are 398 pitchers who have thrown at least 100 fastballs in both 2016 and 2017. Here are all of their year-to-year average fastball heights, and I’ve highlighted the Red Sox pitchers in dark red.

The average increase for a pitcher now on the Red Sox is +2.3 inches. That’s the largest increase in baseball, north of the Nationals’ +1.6. My analysis includes 11 pitchers on the Sox. Of those, 10 have shown some kind of increase in average fastball height, led by Blaine Boyer, who’s up more than six inches. Only Eduardo Rodriguez has thrown his average fastball lower, and that’s been by about one inch. And he’s dealt with some health issues that might’ve somewhat messed up his motion. It seems like a pattern, and now that we’re through almost three months of the regular season, I don’t know how you could call it an accident.

Just how extreme have these Red Sox been? Since we have 9.5 years of pitch-tracking information, that means we have data for 300 individual team-seasons. Now, the 2017 season isn’t complete, so those numbers could change, but this isn’t the kind of thing that strikes me as being particularly subject to noise. Anyhow, this table includes the 10 pitching staffs with the highest average fastballs on record:

Highest Team Fastballs, 2008 – 2017 Team Year Height Red Sox 2017 2.84 Rays 2016 2.75 Red Sox 2011 2.74 Cubs 2008 2.73 Giants 2008 2.73 Red Sox 2009 2.72 White Sox 2010 2.72 Giants 2010 2.72 Dodgers 2009 2.70 Twins 2009 2.70 SOURCE: Baseball Savant

That’s this year’s Red Sox in first, leading last year’s Rays by a full inch. To give this a familiar comparative construct, the difference between first and second place here is the same as the difference between second place and 22nd. It’s correct to say the Red Sox have done something extreme, and although it’s not something you’d necessarily notice in the flow of things, and although it’s not the whole reason why the Red Sox have been successful, every pitch works together, and these pitches have forced hitters to raise their eye levels.

Making the Red Sox all the more interesting: By average fastball height, they rank first in baseball in zero-strike counts, one-strike counts, and two-strike counts. However, in terms of just fastball rate, the Sox rank 29th in baseball in zero-strike counts. They move to seventh in one-strike counts, and then finally first in two-strike counts. The Red Sox are clearly using the high fastball as a putaway weapon, and that explains why they lead baseball in fastball strikeouts, by a margin of 74. Once again, over the course of an individual game or series, it might not be something that stands out, but there’s no mistaking the strategy now, with 75 games in the bag.

The Red Sox have pitched well because they have good pitchers. But they’ve also adjusted those pitchers, making tweaks of varying magnitudes, mostly in the same general direction. These Red Sox fastballs have been thrown higher than any other team fastballs we’ve seen in recent history. It’s not a mistake, and neither is Boston’s place in the standings.