In the second of their two deals on Friday, the Phillies acquired Kyle Backhus from the Arizona Diamondbacks. The 27-year-old made his major league debut last June with the Arizona Diamondbacks after working his way through their minor league system as an undrafted free agent out of Sam Houston State University. The 6’4″, 185 pounder has a lanky, athletic frame and throws from a low, unconventional arm slot that gives him a unique look on the mound.

Backhus wasn’t a high-profile prospect early on. At Sam Houston State, he pitched primarily as a starter and signed with the Diamondbacks in 2021. Initially working as a conventional thrower, he gradually shifted to a more sidearm-ish delivery, lowering his arm slot to gain deception and movement on his offerings. That unusual delivery is a key part of his profile and helps offset a lack of premium velocity, particularly against certain hitters. His velocity appears higher to hitters since he gets an extreme 7’2″ extension from the mound when he throws.

In the minors, Backhus had ups and downs with command but flashed a strong strikeout ability at times. His walk rate historically runs above average for relievers, indicating some control issues that he would need to improve to stick long-term. In 2021, Backhus had his first professional season cut short when he needed thoracic outlet surgery – the same issue that sidelined Zack Wheeler in 2025 – and he dealt with an elbow injury in 2024, which caused him to get a late start to his Triple-A season, but he returned to post a decent 3.94 ERA across 32 innings.

2025 MLB Performance

Backhus spent most of the 2025 season with the Diamondbacks’ bullpen, making 32 relief appearances and throwing 25.1 innings with a 4.62 ERA and 1.42 WHIP in his rookie campaign. He struck out 22 batters, walked 8, and surrendered 3 home runs.

One telling aspect of his season was the platoon split: he was especially effective versus left-handed hitters, holding them to a .139 batting average and a .503 OPS in 2025. Against right-handers, Backhus struggled against right-handed opponents to the tune of a .365 batting average against. That sort of profile is typical for a situational southpaw, but Backhus’ numbers are extreme. At Triple-A Reno in 2025, Backhus excelled with a 2.05 ERA and 37 strikeouts in 26.1 innings, demonstrating his ability to dominate a level below the majors when his stuff is well-located.

Pitch Arsenal & Velocity

Backhus works with a three-pitch mix that leans on movement and deception rather than pure power. According to Statcast and scouting sources:

  • Sinker (Primary Pitch): Sits around 91 mph, which is below average by MLB fastball standards but plays up due to his arm angle and release extension. It induces ground balls and heavy sink when located well.
  • Sweeper / Slider: Used as his secondary weapon with significant horizontal movement (often 13+ inches of break). This pitch is slower and more of a breaking offering that can generate swings and misses, particularly from left-handed hitters.
  • Changeup: A change-of-pace that rounds out his mix. It’s a smaller percentage of his repertoire but adds another look, especially to neutralize lefties.

He releases the ball from a unique slot — roughly 9 degrees shallower than league average — and shows above-average extension, which helps his relatively modest velocities play up and makes the ball seem harder to hit from a deception standpoint.

Strengths

  • Unusual Release & Arm Slot
    Backhus’ lower arm angle and long release point create deception and give his sinker and sweeper extra movement, which can be particularly disruptive to left-handed batters.
  • Ground Ball & Soft Contact Potential
    Though his velocity isn’t elite, his sinker induces weak contact and ground balls when on-target, helping limit hard hits in certain matchups.
  • Strikeout Ability at Times
    In the minors, Backhus has shown strong strikeout rates, and when his breaking ball is working, he can miss bats effectively.

Challenges / Weaknesses

  • Velocity & Stuff Grade
    A 91 mph sinker sits near the bottom ninth percentile of MLB fastball velocity, so he lacks a true power arm that can miss bats on pure speed alone.
  • Control & Command
    His walk rates in the minors were higher than average, suggesting that when his release isn’t repeatable or his angles are off, he can struggle with free passes — something that is magnified in the majors.
  • Platoon Limitations
    Backhus has been demonstrably more effective against same-handed batters than righties, which suggests he may be best suited as a situational left-handed reliever (LOOGY) or low-leverage matchup weapon, rather than a multi-inning high-leverage option.

Outlook

Kyle Backhus profiles as a left-handed relief specialist with an atypical delivery and a pitch mix that relies on movement and deception. He will likely compete for a bullpen role with the Phillies in 2026, where his ability to neutralize left-handed power bats could carve out a niche. Sustained success will hinge on improved command, limiting walks, and maintaining deception to offset below-average velocity.