3 rentals the Mariners could Use to restock the bullpen

The Mariners' pen has been marred by injuries, but we have seen unexpectedly strong performances from Austin Voth and Trent Thornton. Voth made the club, largely due to Matt Brash getting TJ surgery, and has put up a 3.16 ERA in 24 appearances. Thornton, who throws his sweeper more than any other pitch in his mix, is in the 86th percentile in barrel rate, exit velo, and hard hit %. While these performances are encouraging, it would be unwise to rely on these arms for high-leverage situations over a full season.

We're expecting Santos back in July, but the Mariners could use a right-handed reliever with high-leverage experience. If Munoz does re-aggravate his lower back or if there is another unforeseen injury, it'd be great to have another righty in front of Stanek on the depth chart. Here are three relievers we can categorize as "rentals" since they are free agents in 2025.

Option #2: Paul Sewald

Imagine if the Mariners got their old closer back? Sewald hasn't been healthy for a good portion of the year but has a 2.57 in 31 regular season games for the Snakes. Paul is a prime example of the Seattle pitching lab, with a 5.50 career MLB ERA with the Mets in 125 appearances before closing 52 games for the Mariners over a three-year period. Sewald has a two-pitch mix, a 91 MPH four-seam, and a sweeper. He's a non-traditional closer without a big fastball similar to the Yankees closer, Clay Holmes. It may not be en vogue, but a closer needs to get outs. Who cares if the four-seam is 91 or 98, right?

If the Diamondbacks continue to fall down the Wild Card ladder, there's really no way Sewald stays in Arizona. Too many contenders will bid for his services, as guy with 9th inning experience who doesn't have a huge salary figure. Last year, he had a 30%+ K rate on both pitches, but that sweeper is what really makes Sewald special as a reliever. This is Paul's year to test the market, so he has a chance for a nice payday if he can show flashes of dominance down the stretch. What better place for the occasion than the park where he made himself a brand name reliever?

Option #3: Dylan Floro

The Nationals' pen has been sneaky competent this season, and Dylan Floro has been a huge part of that. He's carrying a 1.19 ERA this season in 30 games, he's been nails for over two months. He struggled last year, with a 4.76 split between the Twins and the Fish. He's only got 32 career saves, but he won't command the same price as a closer like Sewald. Floro will probably cost close to nothing, and relievers are difficult to gauge. My feeling about it is that most bullpen arms have great years and bad years. This looks like a career year for Floro, and I expect that to continue to a certain extent.

Floro is a sinkerballer, throwing it 46% of the time. He also throws a slider, four-seamer, and changeup, but his slider and sinker are his two best pitches. His 48.9% GB Rate is 77th percentile this season, while his 1.1% barrel rate is 99th percentile. That kind of consistent soft contact and groundballs mean more double plays and pop-outs.

Floro is in the bottom 2% in chase, and he doesn't generate a ton of swing and miss. He's going to rely on his ability to generate soft contact for outs, but that complements the skillsets of Santos and Munoz quite well. I love this proposal because of how realistic it is, the Mariners could get Floro for a project or org depth guy. Not much to give up, but it would be a huge lift for this bullpen!