Rotation, Bullpen, or Nashville: Analytically Breaking Down Aaron Ashby’s Arsenal

[Michael Trzinski]

Image courtesy of © Jayne Kamin-Oncea-Imagn Images

Aaron Ashby is entering his fifth year in Milwaukee and has been an above-average pitcher for the Brewers, posting career numbers of 114 ERA+ and a FIP of 3.46. Let’s say, for the sake of argument, that Nashville is not a realistic option, as in, ‘he’s too good to send down.’ Where will he fit into Milwaukee’s plans?

Ashby was a fourth-round pick in the 2018 draft out of Crowder College in Neosho, Missouri, and made good progress through the Brewers chain, arriving in Milwaukee in just his third year, and has been a solid contributor ever since.

The Brewers have two main questions with their pitching staff: who is going to start, and who is going to stay in Milwaukee?

Let’s answer the first question. Currently, the Brewers have six southpaws that have the versatility to make the rotation or pitch out of the pen. Newcomers Kyle Harrison and Shane Drohan came over in the Caleb Durbin trade from Boston, joining Robert Gasser, Angel Zerpa, DL Hall, and Ashby. All these guys could potentially join the rotation, or they could reside in the pen.

Back in 2022, Ashby made 19 starts for Milwaukee. He averaged nearly five innings per start, striking out at a high rate of 26.2%, but unfortunately, his 10.4% walk rate was pretty bad. Last year in 43 appearances (including one opener game) he whiffed 28.1% while improving a little on his walk rate, dropping it to 8.9%.

Ashby began spring training last year as a starter but suffered an oblique injury and missed the first third of the season. When he came back, he was inserted into a regular bullpen role, pitching in all leverage situations.

Realistically, Quinn Priester, Brandon Woodruff, Chad Patrick, and Jacob Misiorowski are front-runners for the first four starting spots. Logan Henderson and Brandon Sproat are on the periphery. They are all right-handers. Add to that Harrison, Gasser, Ashby, Zerpa, Hall, and Drohan, and you have nearly a baker’s dozen of arms to choose from. Some will get injured, some will underperform, and before you know it, the Brewers could be scrambling to cobble a rotation together. Let’s hope that doesn’t happen.

Aaron Ashby's Stuff

Ashby depends heavily on his sinker, which he throws over 50% of the time, and backs it up with his curveball, which he throws once every four pitches. His most effective pitch is his curveball, which has a 7.6" drop, more than the major league average. It produced 27 strikeouts for a K rate of 47%. His slider has big movement as well, 9" more than the major league average. Ashby has changed his arm angle over the years, going from high-three-quarters in 2022 when he was a starter to a more over-the-top guy last year with an arm angle of 51%.

Aaron Ashby's Pitch Arsenal

Ashby uses his sinker and curve three-quarters of the time overall, while using his changeup at a 12% rate, while the slider (8%) and four-seam (2%) are the lesser-used pitches in his repertoire. He relies more on the sinker to lefty hitters (58%) and doubles the slider offering up to 18%. When facing righties, the slider and the four-seam go in the back pocket (5% total) while the curve and slider come out half the time, along with the old reliable sinker at 47%. That sinker gets beat into the dirt more often than not (62%), and with an infield like the Brewers have, that is a good thing. 

Year	Pitch Type	#	# RHB	# LHB	%	MPH	PA	AB	H	1B	2B	3B	HR	SO	BBE	BA	xBA	SLG	xSLG	wOBA	xwOBA	EV	LA	Spin	Ext.	Whiff%	PutAway%
2025	Sinker	530	305	225	51.3	97.5	136	119	29	24	2	1	2	21	101	.244	.259	.328	.354	.291	.311	90.2	-1	2151	5.3	16.4	22.8
2025	Curveball	273	192	81	26.4	82.2	57	49	7	5	2	0	0	27	22	.143	.150	.184	.185	.219	.225	88.0	3	2737	5.3	43.9	34.6
2025	Changeup	122	120	2	11.8	91.4	38	35	10	6	3	1	0	9	26	.286	.250	.429	.353	.325	.282	89.2	4	1902	5.3	31.3	25.0
2025	Slider	84	14	70	8.1	84.2	31	28	6	5	0	0	1	17	11	.214	.140	.321	.242	.277	.218	76.2	0	2661	5.3	51.5	29.3
2025	Four Seamer	24	17	7	2.3	96.9	8	7	2	2	0	0	0	2	5	.286	.189	.286	.207	.307	.243	78.8	-12	2263	5.3	28.6	11.8
2024	Sinker	216	136	80	44.6	96.2	56	49	12	9	2	0	1	8	42	.245	.211	.347	.327	.297	.297	90.4	1	2120	5.2	12.6	15.1
2024	Changeup	99	91	8	20.5	88.8	27	23	5	1	3	0	1	4	20	.217	.252	.478	.422	.337	.339	86.5	6	1775	5.2	36.4	13.3
2024	Curveball	93	77	16	19.2	82.2	14	14	1	1	0	0	0	9	5	.071	.161	.071	.241	.063	.174	94.6	-5	2636	5.3	42.9	34.6
2024	Slider	66	26	40	13.6	83.2	19	18	2	1	1	0	0	12	6	.111	.138	.167	.277	.149	.201	85.6	9	2541	5.2	43.8	35.3
2024	Four Seamer	10	9	1	2.1	96.9	3	3	0	0	0	0	0	0	3	.000	.155	.000	.467	.000	.255	95.4	32	2214	5.3	0.0	0.0

What Should Aaron Ashby's Role Be in 2026?

In his major league career, Ashby has appeared in 97 games, of which 26 were starts. He started 66 times in the minors among his 95 appearances, so he definitely has the chops to fit into the rotation. Given the heavy right-handed presence in the tentative rotation, manager Pat Murphy will probably be looking to insert one southpaw into that mix.

The question is: which of the groups listed above will be that left-hander? I would put Harrison or Gasser at the top of that list, but given an underperformance and the likelihood of an injury or two, you might as well flip a coin or roll the dice to decide.

No matter where he ends up, Ashby will play a huge role for the Brewers in 2026. 

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[Jason Wang]

I think they might keep him in a similar role as last year where he was coming out of the bullpen for multiple innings. With a young rotation that could still have some stamina to build, it's a perfect opportunity to use his length without stretching him too far. 

Over the past few seasons, he has posted a 2.37 ERA over 95 innings in 57 appearances. He's really good the first time through the order but I feel like he lacks the depth of arsenal to be a rotation guy. In 2025, only his sinker and curveball contributed positive run value.

[Team Canada]

15 hours ago, Michael Trzinski said:

Let’s say, for the sake of argument, that Nashville is not a realistic option, as in, ‘he’s too good to send down.’ Where will he fit into Milwaukee’s plans?

It's not "for the sake of argument," it just goes without saying. It's weird to even have Nashville in the title of this article at all.

[wiguy94]

Bullpen ace please. 80-100 innings out of the pen being used as a multi-inning weapon.

[MattK]

4 hours ago, wiguy94 said:

Bullpen ace please. 80-100 innings out of the pen being used as a multi-inning weapon.

Completely agree. Indeed, with the starting pitching depth, shouldn't the Crew have 2 or 3 of those types in the pen, so their are only a few 1 inning pitchers?