Cincinnati Reds relief pitcher Tony Santillan (64) Michael McLoone-USA TODAY Sports

The Reds announced Tuesday that right-hander Tony Santillan has been designated for assignment. His spot on the 40-man roster will go to utilityman Alejo Lopez, who has had his contract selected from Triple-A Louisville. Outfielder Michael Siani was optioned to Louisville to clear active roster space.

A second-round pick back in 2015, the now-26-year-old Santillan ranked among the Reds’ top farmhands for several years before making his big league debut in 2021. He looked to be a potential mainstay in the bullpen after pitching 43 1/3 innings of 2.91 ERA ball with a hefty 29.5% strikeout rate. Santillan’s 11.1% walk rate was in clear need of improvement, but it was nonetheless an impressive debut campaign for a prospect whom the Reds viewed as a potentially notable part of their future.

As is so often the case, however, injuries have intervened and radically altered the equation. Ankle surgery, a stress fracture in his back and a knee strain have combined to limit the righty to just 23 big league innings since that debut. He’s posted a 5.09 ERA during that time, fanning just 19.3% of his opponents against an alarming 14.9% walk rate. Santillan has just 3 1/3 MLB frames under his belt this season and has otherwise spent the year in Louisville, where he’s been clobbered for a 9.26 ERA in 23 1/3 frames with nearly as many walks (22) as strikeouts (28).

Santillan still throws hard, averaging 96.1 mph on his heater over the past two seasons. He’s posted a solid 11.6% swinging-strike rate in his MLB career and clearly has shown promise at times, but he’ll be out of minor league options next season and the Reds likely wouldn’t have gone through the entire offseason dedicating a 40-man spot to him anyhow. They’ll have no choice but to place Santillan on waivers now, and any team that claims him can keep him in the minors for the remainder of the year. He’d have to break camp on that team’s Opening Day roster next year or else again be designated for assignment, however.

As for the 27-year-old Lopez, he’ll join the Reds for a third straight season. He’s hit for a solid but empty .262 average in 179 career plate appearances, getting on base at a below-average .307 clip with just a .321 slugging percentage. He has big-league experience at second base, third base and in the outfield corners. He’ll give the Reds a contact-oriented bench bat who’s fanned in just 14.6% of his career plate appearances but also walked at a well below-average 5% clip.

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