One Big Thing: Kody Funderburk's Lower Arm Slot Might Have Unlocked a Bright Future

[Matthew Trueblood]

Image courtesy of © Matt Blewett-Imagn Images

Don't lose sight of this: Being a good relief pitcher in the major leagues is hard. That said, it's not as hard as being a good starting pitcher, or a good shortstop or a good cleanup hitter. Relievers are role players. They enjoy the advantages of playing at a higher baseline level of effort, relative to the absolute maximum they can do, and of being sheltered (most of the time) from the worst matchups they might face if their manager weren't carefully selecting the situations in which they're used.

You really just need one good thing, to be a good reliever. You have to have a calling card. That's not to say that overspecialization is advisable. In the age of the short start and the three-batter minimum rule, it pays to be versatile and durable. Still, because relievers play in such short bursts and under such favorable conditions, having one really good trait can be enough to keep you around. It might even be enough to make you a positive contributor on a winning club.

Kody Funderburk entered 2025, though, without that one thing. He was an up-and-down relief arm in 2024, used more or less as cannon fodder. The Twins didn't view him as a well-built weapon against lefties, but nor has he ever been a reverse-splits guy. He does get lots of ground balls, but because he's generally struggled with walks and doesn't miss bats, he was always a bit too much of a risk to bring into a high-leverage situation, even to get a lefty batter out or to induce a double play. He was missing the kind of ingredient that cements a player in the majors, and keeps them off the shuttle to Triple A.

Over the summer, though, he found it. Funderburk slightly lowered his arm angle and his release point this season. As a result of the mechanical tweak, he achieved more extension at release, which added a half-tick to his fastball. The change in angles also made it easier for him to keep his primarily east-west arsenal on the plate. Fully 53% of his pitches this year were in the strike zone, according to Statcast; that's up from just over 50% in 2024.

He still walked batters at about the same rate, and there's work left to do with his sequencing to better convert the increase in strikes thrown to a decrease in free passes, but Funderburk no longer found himself working from behind in so many counts. He kept the ball in the park much better, because hitters couldn't sit on his cutter, and indeed, the lower angle opened up much greater usage of his sinker and changeup, each of which helped him seek grounders.

Were Funderburk pitching in front of a better defense, he'd probably have put up even better numbers this season. As it was, he finished the campaign with a 3.51 ERA in 41 innings for the major-league team, most of them pitched after the trade deadline fire sale. That's sustainable. In fact, he can improve upon it next year. The Twins should pencil him into their relief mix heading into the offseason, which is a concrete improvement from where he slotted into their depth chart as recently as three months ago.

It would be good, I think, to visualize this arm angle change in a couple of ways more concrete than that numerical chart. First, let's compare the arsenal Funderburk threw to lefties in 2024 with that for 2024, by looking at an animation of his pitch mix coming toward a lefty from an imagined lefty's vantage point.

Slightly reducing the arm angle actually makes the cutter separate from his other offerings more than it did last year, for Funderburk, but that only sounds like a bad thing. It's actually exactly what he needed. Getting around the cutter a bit more allows him to drive it to the outside edge against lefties, while his sinker runs nicely back to the inside corner. He emphasized his slider more this year, at the expense of his sweeper. That sounds like a distinction without a difference, but it's not. Firstly, as he lowered his arm angle and brought his sinker forward as his primary fastball, Funderburk naturally went to the breaking ball that better tunnels with the sinker. His sweeper, as you can see in the upper half of the image above, tunnels better with the cutter; he's more deceptive with the slider taking over.

Secondly, though, making the slider a primary weapon to lefties also made it easier to maintain that pitch and execute it consistently to righties. One challenge for a reliever is that their arsenal needs to overlap, from a matchup perspective, more than a starter's does. A starter who has three pitches that work against lefties and three that work against righties will get enough reps and enough time between starts to hone all of those offerings. A reliever has to be ready at all times, which usually means keeping the repertoire streamlined and sharp for whoever digs into the box.

Here, you can really see why the sinker and cutter disguised one another better in 2025 than in 2024. The sweeper is turning into more of a curve, a pitch thrown ball-to-strike to catch the batter off-guard and steal a call. The slider and changeup stay on plane with the sinker and cutter longer, from a righty's perspective, despite the lower slot.

Here's a glimpse of the change in video form. First, watch Funderburk throw a sinker to a lefty in 2024.

That's not a bad way to shoot for that corner, but Funderburk decidedly missed. Now, consider the way he went after another lefty, in August.

Though neither the velocity nor the simple movement metrics on that sinker changed much this year, it's easy to see why Funderburk now likes it enough to be throwing it more often. It's livelier. It's also more likely to find the zone. Let's freeze on the release point of each of those pitches.

You can see the difference, in the angle of the arm relative to the shoulder. It's much harder to see from this angle, but Funderburk is also getting a bit deeper into his legs as he flies down the mound. Thence comes his better extension and the added deception of a change in release angle.

Funderburk is not a future closer. His upside looks something like what Caleb Thielbar gave the Twins for a few years. Until this season, though, Funderburk looked like he might never get off the roster bubble. Changing his mechanics (and letting that inform changes in approach) got him off that bubble. It was a small thing, but it became a bigger one for both the player and the team after the July shakeup. In 2026, it might feel like a fairly big thing to have done.

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[tony&rodney]

Funderburk did pitch much better in the end of the season. He should be on the main roster and hopefully he continues to be competent. Caleb Thielbar is a good relief pitcher, so we can wish solid results for Kody.

[jmlease1]

He does look like he can be a good reliever in a competent bullpen. While I'd prefer for him not to be the only LHP in there, the mechanical change followed by improved results have me hopeful his performance after the deadline wasn't just small size but a reflection of what he's actually capable of now.

He was one of the very few bullpen positives we saw after The Decimation. If he can be a Thielbar type for the next several years that would be very useful.

[Doctor Gast]

Thank you, Matthew, for explaining how Funderburg improved. By his stats, we could see that he was doing something more successfully, but didn't know what. RPs are a different animal, but that's the key: know what each is good at & have them focus on that (not forcing them into something they are not).

It's amazing how Theilbar was good, then not good, then left MLB. He returned & was dominant, he slumped & returned. Last year Twins gave up on him & he returned with the Cubs & was miraculous. Good for him.

[Eris]

I thought this was one of the aspects of pitching that Craig Breslow demonstrated later in his playing career. By lowering his arm angle he could increase revolutions and therefore movement on his pitches. 

[DocBauer]

There are a handful of 26yo and under LH possible pen arms that will be sitting at AAA this year, or AA to begin the year like MacLeod, Bragg, and Nowlin. Nothing proven yet to be sure, but some guys that have some decent stuff if they can find a little more consistency. 

And hopefully, there's a Coulombe re-sign, or someone similar, for around $3-3.5M. 

Thielbar has been mentioned. If this new arm angle has indeed raised Funderburk's game to a higher level, I'd ecstatic if he was Thielbar for 2-3 years. I don't know that he's actually reached that level, but if he has/could, that's a huge win for an arm that has shown potential but no consistency. 

Crossing my fingers he might have that level of production going forward. 

[miller761]

We need multiple good left hand relievers. The good playoff teams have 2 or3. Hopefully Kody can fill one of those roles.

 

[Permanent Twins Fan]

Kody appeared to unlock something in the second half. If he continues that into next season, the Twins will have a much needed high end bullpen arm. The Twins will have to build a bullpen in 2026, and as of now Kody is probably the arm from the 2025 pen that I trust the most. They will need him to be good in 26. 

[Linus]

I’m glad he pitched better after the break. He’s earned a spot in the pen next year. I remain skeptical that this level of performance is the new Funderburk. 

[stringer bell]

Fundy threw a lot more strikes, both called and swinging, which greatly helped him net more outs. Lower arm angle? Sure, I guess. It appeared to me that he had better command and deception lt appears he’ll be relied on in 2026. 

[Richie the Rally Goat]

Wow, that was minutiae! Thanks Matt, great job simplifying it for us laypeople. Very good read

[Doctor Wu]

15 hours ago, DocBauer said:

There are a handful of 26yo and under LH possible pen arms that will be sitting at AAA this year, or AA to begin the year like MacLeod, Bragg, and Nowlin. Nothing proven yet to be sure, but some guys that have some decent stuff if they can find a little more consistency. 

Good examples. I still think that Nowlin could turn into a useful bullpen arm ... but as you noted, he needs to find that consistency. 

[Doctor Wu]

Were Funderburk pitching in front of a better defense, he'd probably have put up even better numbers this season.

True, but then again. ALL of our pitchers could have benefited from a better defense. 

[TopGunn#22]

When Funderburk initially came up he looked pretty good.  Then the league established a "book" on him and he (or the Twins coaching staff) seemed to be slow in countering.  Late this season he seemed to really turn a corner.  Throwing strikes at a higher clip is always helpful for a pitcher.  Matthews, Bradley and Abel could become MUCH better if they can achieve better command and throw strikes consistently.

We saw evidence of that in each of their last starts.

Hopefully, the Twins will make some trades to get some better OF.  I'm not convinced Brooks Lee is an every day SS.  I'm not sure Culpepper is a BETTER SS but he's certainly more athletic.  I think Marek Houston is a future Gold Glove winner at SS if his offense allows him to play in the major leagues.

Once the Twins field a better defensive team, their starters and relievers across the board will perform better.  It's tough to field a good defensive team when over 50% of your fielders profile as DH's.  

Even with Funderburk, I'd like to see the Twins bring back either Thielbar or Coulombe.  Having more than ONE reliable Lefty in the pen should be a goal.  

[terrydactyls]

Funderburk raised his strike % from over 50% to 53%.  Sounds good until you dig deeper.  According to Statcast, Funderburk threw roughly 750 pitches in 2025.  Using last year's % (rounding down to 50%), that would be 375 strikes.  Using the newer % of 53%, he threw 397 strikes - a difference of 22 more strikes.  Over the 41 innings he pitched, that would mean roughly 1 additional strike every two innings.  That doesn't seem like much of a change.

[gman]

Did Funderburk make his changes and improvements after he came up at the end of the season or before at Triple A? I'd like to acknowledge the coach who worked with him to make those improvements.