Rule 5 picks aren’t known to be guaranteed successes. Of course, there are the obvious exceptions, like Odubel Herrera, Marwin Gonzalez or Hector Rondon, but for every success, there’s a Tyler Goeddel, a Jabari Blash, a Taylor Featherston. Generally speaking, the Rule 5 Draft is a good way to ensure players aren’t buried on a roster, but in terms of long-term contributors, not much often comes of it.

With that said, let me introduce to you right-handed reliever Brandon Brennan. He was the 13th overall selection in the 2018 Rule 5 Draft by the Seattle Mariners, who were so interested in bringing him aboard that they made the pick even after missing out on signing him as a minor league free agent.

When the decision to draft Brennan was made, Mariners Vice President of Scouting Tom Allison expressed his enthusiasm to Greg Johns of MLB.com. “Opportunity is probably what he needs the most, and we have that to give him,” Allison said.

What I love most about this quote is how accurate it is four months later. Brennan not only made the Mariners’ Opening Day roster, but he’s been superb so far here in the early going, making the most of the opportunity that Allison said Seattle had to give. Granted, he’s made just nine appearances and pitched just 12.1 innings, but the results have been there. Brennan has pitched to a 0.73 ERA (one earned run allowed) and 2.57 FIP, with 13 strikeouts (29.6 K%) to just two walks (4.6 BB%) across the 44 batters he’s faced. Hitters are hitting just .143 (6-for-42) against him. Anecdotally, he’s been called “the Mariners’ best reliever this season.”

Clearly, Brennan has pitched well enough so far to warrant the team holding onto him; remember, Rule 5 picks must remain on the selecting team’s roster for an entire season in order for said team to gain control over the player. He has established that he can get major league outs. And, for a Mariners team that, despite what their current record shows, probably won’t contend this season, Brennan could be a valuable piece going forward, in 2020 and beyond. The potential upside has already been demonstrated, and that’s good for both Brennan and the Mariners.

At FanGraphs, though, my job isn’t just to tell you that Brandon Brennan has been good. It’s also to explain — to the best of my ability — why he’s been good. On April 12, Johns wrote about how Brennan has thrived with a reworked changeup, a pitch that he has already used 45.0% of the time so far. It has generated solid results: 10 of Brennan’s 13 strikeouts have come with the changeup, along with a .111 batting average against (two-for-18, both singles). A lot of these numbers won’t be sustainable over the rest of the season, but what we can definitively say is that Brennan’s changeup has already established itself as a pitch that can make hitters look silly. Check out what it did to a new-and-improved Yoan Moncada, who has made real strides in his plate discipline this season:

So, yes, it’s a nasty pitch. There’s a lot more that goes into being a good pitcher than just having nasty stuff, but it is, by no means, a bad thing to have a changeup that can fool a major league hitter as badly as Brennan fooled Moncada.

That got me thinking, though: what pitchers throw a changeup similar to Brennan’s? Finding the answer to this question could help us better determine what’s to come, answering questions like, “Is Brennan’s changeup truly special?” or “Are we about to see some serious regression?”

Let’s break it down. As you can see in the Moncada video, Brennan’s changeup has a knack for breaking well away from left-handed hitters (and towards right-handed hitters). This is supported in the data, as Brennan is sporting -9.7 inches of horizontal movement on his change — meaning that his changeup breaks heavily towards right-handed hitters. This represents the 10th-most horizontal break in this direction of any changeup in baseball among pitchers with at least 10 innings. As we’ve seen with Jimmy Yacabonis, though, horizontal break alone doesn’t always yield excellent results. (Yacabonis, in fact, ranks fifth on this list.) But for Brennan, it has, and this could be due to much better command and control than Yacabonis exhibits.

We’ve now established that Brennan has major horizontal movement on his changeup. But let’s talk about what he doesn’t have, and that is vertical movement. Despite his changeups moving, on average, by 9.7 inches in the x-direction, they barely move in the z-direction, with an average of just 1.2 inches of z-movement this season. (The major league average changeup moves about 2.9 inches towards righties in the x-direction and 3.5 inches “up” in the z-direction.)

So, clearly, something unique is happening here. In order to find a comparable changeup for Brennan’s, I compiled a list of the changeups of every major league pitcher this season and found pitches that are within 0.5 inches of both x- and z-movement to Brennan’s pitch. That leaves us with two pitchers: Pablo Lopez and Max Scherzer, with Scherzer’s movement (9.6 inches in the x-direction; 1.4 inches in the z-direction) being almost identical to Brennan’s.

The Scherzer comparison is obviously something that jumped out at me, hence the title of this very article. He’s one of the best pitchers in baseball, and he likes throwing his changeup, using it 18.6% of the time. Scherzer is a starting pitcher, so he can’t rely on a two-pitch repertoire like Brennan can, but the fact that the changeup is Scherzer’s second-most frequent offering tells us a lot. Namely, that Scherzer — one of the best pitching minds in baseball — thinks his changeup is solid pitch. If Brennan’s changeup is similar to Scherzer’s, that can’t possibly be a bad thing.

Let’s present some video evidence, though. Here’s a short GIF of a Scherzer changeup above the previously-seen Brennan GIF, for comparison’s sake:

There really might be something here. Even the two pitchers’ changeup spin rates — 1,627 for Scherzer, 1,709 for Brennan — are decently close, and the 82-point difference between them becomes even less significant when you consider that major league changeups have ranged between 1,214 (Edinson Volquez) and 2,892 (Adam Ottavino) revolutions per minute this season. An 82-point difference in a 1,678-point spread is relatively insignificant.

This is where Brennan becomes even more interesting. Because if his changeup is anything like Scherzer’s, hitters are going to have a really tough time hitting it. So far this year, batters have posted a .340 wOBA against Scherzer’s changeup, but the underlying numbers — like a .231 xwOBA and a .177 xBA — suggest that it’s actually been a very effective pitch. He’s also generating a 20% swinging strike rate and an 81.3% ground ball rate with it, both incredibly good numbers.

Here’s a batted ball comparison between the changeup for Scherzer over his entire career and for Brennan in his short 2019 sample:

Batted Ball Results, Changeups Player LD% GB% FB% IFFB% Scherzer Career 19.3% 55.0% 25.7% 18.2% Brennan 2019 16.7% 83.3% 0.0% 0.0%

Clearly, if Brennan gets batted ball results anywhere near what Scherzer has been able to generate, he’s going to be in great shape going forward. It’s hard to read too much into what he’s done so far, but if he regresses to Scherzer territory, he’ll still remain as an extremely effective pitcher. Scherzer consistently ranks among the best pitchers in changeup xwOBA every single year.

And, now here’s a plate discipline comparison between the two:

Plate Discipline Against, Changeups Player O-Swing% Z-Swing% Swing% O-Contact% Z-Contact% Contact% Zone% SwStr% Scherzer Career 41.7% 72.3% 52.8% 60.3% 83.0% 71.5% 36.1% 15.0% Brennan 2019 44.7% 83.3% 59.7% 23.5% 60.0% 43.2% 38.7% 33.9%

Here, we finally see some differences emerge. Scherzer’s changeup has proven to be hittable, when in the zone, evidenced by the 72.3% z-swing rate and the 83.0% z-contact rate. Brennan’s, on the other hand, has been swung at even more when in the zone than Scherzer’s, and yet hitters are still only making contact on it 60.0% of the time. That’s a further testament to its nastiness, and how hard it can be to hit even when it’s in the strike zone. Of course, this all comes with the caveat that it’s still early in the season, but these are excellent figures.

On the whole, I don’t think many of us would have expected Max Scherzer to be a good comparison for Brandon Brennan. Those two pitchers are so different in so many ways, but it’s quite fun to be able to identify a point of similarity between a three-time Cy Young award winner and a newly-minted Rule 5 Draft pick. Brennan probably won’t keep pitching quite this well, but so far, he’s making the most of his opportunity.