Mariners' latest waiver claim gives them badly needed bullpen insurance

The past few weeks haven't been kind to Mariners fans. Seattle's playoff odds have continued to slide as a result of their failure to perform on the road, and they've given up significant ground in the AL wild card standings to the Texas Rangers, who are now just half-game back.

At this rate, the team is just a few losses away from a catastrophic collapse, and the organization is scrambling to do what they can to stay afloat.

Mariners don't have much to lose with new reliever

The most recent step taken by the front office was to acquire left-handed reliever José Castillo off of waivers from the New York Mets. Typically, a player claimed off of waivers is not who you expect to have much of a positive impact, but Castillo isn't your average waiver claim.

After a rough start with Arizona, he was traded to the Mets and posted a 2.35 ERA and 2.62 FIP over 16 appearances with the club. With no remaining options, he was designated for assignment four times this year by the Diamondbacks and the Mets before finally being claimed by the Mariners.

Armed with a sharp slider and movement-heavy sinker, Castillo aims to maximize soft contact. With a fastball velocity in the low-90s and below-average whiff rates, it's the most effective way for him to pitch. Thus far, he has done a pretty good job of leaning into his strengths, holding batters to a 5.7 barrel rate and posting a ground ball rate of 54.3.

If he's so good, then one might ask why he was designated for assignment so many times and eventually given up for free? The main concern with Castillo is whether he'll be able to remain competitive at a big league level. His professional career has been sandbagged by injury woes and from 2019-2024, he pitched just two major league innings. He had great numbers in New York but still had a WHIP of 1.76 and a 12.3 H/9. The Mets saw him as an expendable arm that was expected to give out eventually and with the postseason quickly approaching, prioritized giving roster spots longer term pieces instead.

For the Mariners, it's hardly a time to be picky about relievers, especially with it comes to lefties. Trade deadline acquisition Caleb Ferguson has performed less than ideally, pitching to a 5.25 ERA over 12 innings, and even Gabe Speier has posted a gruesome 9.64 ERA over the last two weeks. With few alternatives, the Mariners are happy to take a flier on a project with potentially high upside.

The pitching picture has rapidly become an area of concern for the team and it doesn't look like things will be turning around soon. With a 4.96 ERA over the past 30 days (24th in MLB), what was once the pillar of the team has become its main weakness. If the Mariners want to have any chance of salvaging their postseason hopes, a return to form is necessary and perhaps a new arm in the first step to getting there.