Even if you’re not a Boston Red Sox fan, you’re probably familiar with the Xander Bogaerts story. Big-time top prospect. Shortstop who has power. Pretty good plate discipline. Did some nice things right after his debut. Got off to a strong start in his first full season. Then: the collapse. I don’t need to give you the numbers — just imagine really terrible numbers. You’re there! So went Bogaerts, prior to his 2015.

This, though, has been a year of far more consistency. And far more promise.

It’s also been a year of change. Of significant change. Of major super massive change. We talk about players making adjustments all the time, but seldom do players make adjustments as big as Bogaerts has. If you’ve been paying attention, this isn’t exactly anything new. Owen hit on some of this in June. A player like Bogaerts, on a team like the Red Sox, doesn’t make a big change without a bunch of people noticing. But it’s one thing to notice what’s happened. It’s another to understand how dramatic this is.

Evidence of Bogaerts making changes isn’t hidden. It’s slathered all over his player page, and you’d have to be an idiot not to notice. I mean, for example, he’s lifted his wOBA from last year by 40 points. He’s cut his strikeout rate by nine points. His ground-ball rate has spiked to something more in line with what he did in the minors. So many signs are there. One could argue all the possible signs are there. There are lights and alarms and people scurrying in a panic.

Pick any individual statistical change, and you can write about the year Bogaerts has had. But I’ve settled on my favorite indicator. I’ve written a little bit about pulled grounder rate. You have to kind of dig for it on our leaderboards, but I like it because it’s a tricky thing to fake. Certain hitters with certain swings are going to pull a certain amount of their grounders, and while there’s room for some noise, the numbers are very much swing-specific. Over a big-enough sample, pulled grounder rate isn’t going to lie. If it stays the same, the hitter might not have changed much. More importantly, if it doesn’t stay the same, the hitter probably did something.

So, a plot. We have information going back to 2002. Below, you’ll see pulled ground rates for hitters who hit at least 100 grounders in consecutive seasons. This gives you some idea of the number’s “stickiness.” Quite obviously, Bogaerts is highlighted.

Two years ago, Bogaerts pulled more than two-thirds of his grounders. This year, he’s just above two out of five. If you just think about that for a moment, maybe it doesn’t mean much to you — this isn’t a normal, popular statistic. So let me put it in some context. I have a sample of 2,433. That’s 2,433 cases of a player hitting at least 100 grounders in consecutive seasons between 2002 and 2015. Here are the biggest season-to-season drops:

Bogaerts has the biggest decline, and he has the biggest decline by an awful lot. While I know his season isn’t over, it’s close enough that this shouldn’t change very much at all. This doesn’t happen without a major change in swing or approach. Bogaerts has almost forced himself to go the other way. And while the Red Sox haven’t tried to make too many tweaks to Bogaerts’ highly-regarded swing, they have worked on his timing, his balance and his tendency to get ahead of himself. Bogaerts has been a Chili Davis project since spring training. Davis likes where Bogaerts has gotten.

Borrowing from Brooks Baseball, here’s Bogaerts’ 2014 spray chart:

Here’s 2015:

And in case that doesn’t help too much, here’s a .gif of the same images:

Bogaerts did hit balls to the opposite field in 2014, but many of those were accidents, mis-hits or mis-swings. So those balls weren’t hit very well, and they turned into easy outs. The focus this year has been on making sure to stay back and drive more pitches up the middle or the other way, if called for. More balls have been not pulled, on purpose. That’s how you end up with a table like this:

Xander Bogaerts wRC+ by Location Location 2014 2015 Pull 178 132 Center 91 135 Opposite 26 137

Someone like the first guy can be successful. Someone can be successful and extremely pull-heavy; Brian Dozier makes that work. But the recent version of Bogaerts is a lot more balanced, and if last year’s approach were the right one for him, it would’ve been a better season. This has been about discovering, or re-discovering, the opposite field. For a while, Mike Moustakas was drawing the bulk of the attention for learning how to go the other way. He’s increased his hit total to the opposite field from 17 to 46. Bogaerts has increased his from 17 to 59. Not that Moustakas doesn’t deserve credit, but this adjustment isn’t his and his alone.

It’s done wonders for Bogaerts’ plate coverage. Against inside pitches, he’s improved his batting average by 115 points. Against outside pitches, he’s improved his batting average by 71 points. That isn’t all signal. I mean, that isn’t all real, legitimate improvement. Bogaerts has probably had a few too many balls in play drop for hits. But the adjustment is real, quite obviously real, and the really interesting part is what this sets him up to do in the future.

See, Bogaerts turns 23 in a couple weeks. He hit for power in the minors, and on the year he’s sitting on five home runs. This isn’t how people envisioned the Xander Bogaerts finished product, but then, this probably isn’t the Xander Bogaerts finished product. This is a transition state. This is Bogaerts learning pitchers, and learning to stay back. If things go according to plan, the next step is pouncing. Controlled pouncing. From this Baseball Savant tool, Bogaerts’ top exit velocity matches Andrew McCutchen and Kris Bryant, among others. We know the power is in there, but hitters don’t make a lot of changes on the fly, mid-season. This year has been about staying back, and it’s been successful. Next year might be about putting everything together.

From the better approach can come the power. From the power can come the walks. That’s what people envisioned, and though that guy doesn’t exist yet, he’s closer than he ever was a year ago. Bogaerts has made a dramatic adjustment, learning to drive the ball the other way. Now that he’s done that, he can start to hunt for the right pitches to pull. That’ll be 2016’s project.