Mariners pick the most obvious plan possible to fully unlock Jose A. Ferrer

Jose A. Ferrer is in his first spring training with the Seattle Mariners, and the feedback he's getting is basically: "You're a Mariners reliever, so act like one!"

They don't want Ferrer to be afraid of his secondary offerings. He was primarily a sinkerballer with the Washington Nationals, and reporting from Adam Jude of The Seattle Times posits that the Mariners want to see him mix in more sliders and changeups.

It's all there in this quote from pitching strategist Trent Blank:

"The present stuff is there. It’s a real fastball, a real sinker, obviously, that’s (his) carrying trait. He’s always had the slider, and he has a changeup that he’s developing. Those are two things we’re going to see if we can maybe up the usage a little bit, but I could see outings where he just mows guys down with the nasty two-seamer."

Trent Blank

If Blank tipped his hand here, it's how he went to the slider first before nodding to the changeup as a "developing" pitch. It's telling, if for no other reason than Ferrer's pitch usage from last season indicates the opposite is actually true.

In 72 appearances with the Nationals, the lefty used the changeup 21.9 percent of the time. The slider? Only 7.5 percent.

Mariners see Jose A. Ferrer's slider as the key to his evolution

As a general rule, the Mariners don't like relievers who throw straight pitches. Their guys threw four-seam fastballs just 25.8 percent of the time (26th in MLB) in 2025, whereas they threw sliders 32.3 percent of the time (3rd in MLB).

Based on its returns from last season, Ferrer's slider does look like a weapon that should be used more often. Hitters were 2-for-19 with 12 strikeouts against it, with a 52.5 whiff percentage. The latter was a top-10 mark among all sliders thrown at least 50 times.

It might have been the novelty of the pitch that bamboozled hitters more than the shape of it. Among left-handed sliders, only Tarik Skubal beat Ferrer's velocity average of 89.7 mph. However, neither the vertical drop nor the horizontal break on Ferrer's slider were better than average.

Then again, novelty alone might be enough to sustain Ferrer's slider as a more oft-used weapon.

Even if it lacks, say, the exceptional glove-side run of Aroldis Chapman's slider, it's not as if hitters will be able to go up to the plate and sit on it. They'll mainly be protecting against a sinker that sits at 98 mph and with bowling-ball movement. There will also be the changeup, which had a 47.0 Whiff% in its own right last year.

Even though they gave up Harry Ford to get him, the other reality is that the Mariners are playing with house money with Ferrer. If they're correct that he has upside beyond his 4.36 career ERA, then great. If not, then they still have Gabe Speier as their primary lefty reliever.

In other words, they'll live even if this proves to be Gregory Santos all over again.