White Sox Deep Dive: Birmingham Left-Handed Relievers

“Deep Dive” focuses on the depth of each position in the Chicago White Sox organization. Each position is broken into a five-part series:

1. Depth in the rookie levels (Dominican and Arizona)
2. Depth in A-ball (Kannapolis and Winston-Salem)
3. Depth in the higher levels (Birmingham and Charlotte)
4. Under the Radar-type detail on a White Sox player
5. Free agent options

What Birmingham lacks in lefty relief quantity, it makes up for with quality. Here’s a look at the two promising southpaws who finished the year with the Barons.

Ages below are as of April 1, 2022

Birmingham Barons

Zack Muckenhirn
6´0´´
205 pounds
Age: 27

Muckenhirn, a native of Delano, Minn., went 6-1 with a 0.89 ERA with 59 strikeouts during the 2013 regular season, and was a key piece to his team’s run to the Class AA state tournament. He wasn’t highly heavily recruited until his senior season, after which he opted to pitch for the University of North Dakota. He pitched fairly well during his three years there, but caught the attention of scouts as a junior when he walked 14 and struck out 99 in 92 ²⁄₃ innings for the Fighting Sioux (n.k.a. Fighting Hawks) to go along with a 3.59 ERA. As a result, he was selected in the 11th round by the Baltimore Orioles in the 2016 MLB draft.

Splitting his first full year of professional ball with Rookie League Aberdeen and Low-A Delmarva, Muckenhirn was primarily a starter but posted disappointing results (5.13 ERA, 1.60 WHIP, .314 OBA). The Orioles promptly moved him to the bullpen in 2018, where he produced excellent results in A-ball before succumbing in Double-A with Bowie. He pitched well in 2019 in his return to the Bowie Baysox, but produced a 17.18 ERA in his four-game stint with Triple-A Norfolk. Although he was a member of Baltimore’s alternate training site during the 2020 pandemic, he didn’t get the opportunity to pitch in the majors. Then, just days before the 2021 season was slated to begin, he was released.

The White Sox signed Muckenhirn to a minor league deal on May 1, and he was arguably the best full-season southpaw reliever in the team’s minor league system. In 30 games totaling 40 ²⁄₃ innings for Birmingham, he posted an impressive 1.77 ERA and 1.20 WHIP. In those innings, Muckenhirn allowed just 30 hits (.204 OBA) and 19 walks (11.4%) while striking out 42 hitters (25.3%). His ground ball rate was superb, as opponents hit worm-burners 54.4% of the time. Lefties hit .192 against him, while righties fared marginally better (.212). Muckenhirn pitched to contact when nobody was on base (.263 OBA), but bore down with runners in scoring position (.130 OBA).

An Orioles scouting report back in 2016 said this of Muckenhirn: “He’s a four-pitch lefty with a 90-93 mph fastball with good late life at times. He changes speeds well and has some deception in his delivery that get him swings and misses in the strike zone. His change is his best off-speed offering that has good drop and comes in at 79-81 mph. His slider (80-81) is more consistent than his curveball (72-76), but both can flash major league average at times. He works down in the zone well and will move the ball in and out and up and down.”

The White Sox owned a full cupboard of lefty relievers in Charlotte last year, including two with major league experience in Jace Fry and Nik Turley. That depth made it difficult for guys like Muckenhirn to receive a well-deserved promotion, and the White Sox opted to add Anderson Severino and Bennett Sousa to the 40-man roster ahead of Muckenhirn. He likely will begin next year’s campaign with Charlotte.

Andrew Perez
6´2´´
215 pounds
Age: 24
2019 SSS Top Prospect Ranking: 53
2020 SSS Top Prospect Ranking: 34
2021 SSS Top Prospect Ranking: 34

Perez, after a typically unsuccessful freshman season, excelled out of the pen for the University of South Florida during his sophomore and junior years. As a junior for the Bulls, he posted a 2.34 ERA and 1.16 WHIP in 24 relief appearances. In his 42 innings, he surrendered just 37 hits (.233 OBA) and 12 walks (6.9%) while striking out 50 (28.6%). As a result, the White Sox selected him in the eighth round of the 2018 draft.

As an encore with Great Falls and Kannapolis after the draft, Perez combined with both teams for a 2.59 ERA and 1.18 WHIP by allowing 24 hits (.214 OBA) and 13 walks (9.8%) while striking out 31 in 31 ¹⁄₃ innings (23.3%).

The following year, 2019, saw Perez split his time nearly evenly between Kannapolis and Winston-Salem. While his numbers were good throughout, he gave up more hits with the Intimidators but relinquished more free passes with the Dash. Combined with both teams in 41 relief appearances spanning 67 ¹⁄₃ innings, Perez posted a 1.74 ERA and 1.37 WHIP by allowing 63 hits (.239 OBA) and 29 walks (9.8%) while fanning 86 (29.0%). Perez actually fared better against righties (.230 OBA) as opposed to lefties (.265 OBA).

After the minor season was cancelled by the pandemic, Perez pitched the entire 2021 season in Double-A. In 31 relief appearances, he posted a 3.50 ERA and 1.19 WHIP. During his 43 ²⁄₃ innings with the squad, Perez surrendered 40 hits (.238 OBA) and 12 walks (6.5%) while striking out an impressive 59 hitters (31.7%). Opponents hit grounders 35.4% of the time against his offerings, while lefties (.241) and righties (.237) produced nearly equal results against him.

Perez features a 95 mph heater according to Baseball America, along with a slurvy breaking ball. Somehow, he remains overlooked among the high volume of southpaws in Birmingham and Charlotte. It’s difficult to envision where he’ll fit in next year, but the affable Perez has certainly merited a nod to Charlotte.