Forgotten Mariners prospect is now Reds' last hope of winning Luis Castillo trade

Just as no sane person would argue that the Cincinnati Reds are winning the Luis Castillo trade, no sane person would say the Seattle Mariners can't still lose it. Castillo is in sharp decline, and now Edwin Arroyo is forcing himself back into the larger narrative of the trade.

The Reds need a boost amid a sudden freefall to the bottom of the NL Central, and Arroyo is right there as a button they can push. Through 38 games with Triple-A Louisville, the 22-year-old infielder is batting .338 with a .979 OPS and seven home runs.

The appeal of calling on Arroyo is obvious. The Reds have lost eight out of 10 largely because an offense that sputtered through March and April (4.3 R/G) is now sputtering even more in May (3.1 R/G). And with Matt McLain only batting .204, second base might as well be calling out for Arroyo.

It's been a long road back for Edwin Arroyo, who is rising as Luis Castillo continues to fall

Whereas this year is looking like a crossroads for Noelvi Marte, Arroyo's stock is finally getting back to where it was when he was a co-headliner in the Castillo trade back in 2022.

Arroyo was Seattle's No. 3 prospect at the time, and his status as a teenager dominating Single-A ball gave him a ton of helium. But after he began 2023 universally ranked as a top-100 prospect, his productivity stalled out and then he had surgery on his shoulder that sidelined him for all of 2024. Upon his return in 2025, his productivity pretty much remained stalled out.

Coming into this year, Baseball America ranked Arroyo as the Reds' No. 7 prospect and waved him off as a "bottom-of-the-order bat." Given Marte's own struggles to establish himself after a PED suspension in 2024, the 8.2 rWAR the Mariners had gotten out of their first three-and-a-half years with Castillo looked like a mark the Reds' end of the deal might never equal.

Now along comes Arroyo to change the equation. With a new approach and his shoulder back at full health, he's mainly showing there is, in fact, pop in his bat. He's slugging .573, and his exit velocity, hard-hit rate and barrel rate are all above the Triple-A averages.

Meanwhile in Seattle, Castillo lost his mantle as the Mariners' ace in 2025 and is now barely in good standing in the rotation. He began this year with six shutout innings in his first start, and has since allowed 32 runs in 32.1 innings over his last seven. Time comes for all pitchers eventually, and it sure seems as if it's the 33-year-old's turn.

Given that he hasn't even played in the majors yet, it's too soon to anoint Arroyo as the savior of the Castillo trade for the Reds. But now that Marte is out of favor, Arroyo is nothing if not their last best hope.

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