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PEORIA, Ariz. -- Luis Castillo did not begin throwing a new pitch this offseason, oddly making him the glaring outlier among the Mariners¡¯ starting staff.

Pitchers arriving at Spring Training with a new weapon is as clich¨¦ as a guy showing up in ¡°the best shape of his life.¡± Yet for a rotation that could be among the American League¡¯s best, with established arms possessing plus stuff, the breadth of the adjustments is unique.

¡°I've been in a rotation with Zack Greinke, and he's always messing around and creating new pitches,¡± Robbie Ray said. ¡°But I¡¯ve never really seen four-fifths of the rotation [do it].¡±

Castillo aside, Ray, Logan Gilbert, George Kirby, Marco Gonzales and Chris Flexen -- who¡¯s on the outside but is being stretched out -- all showed up with a new toy to tinker with.

Here¡¯s a look at what each guy added and why:

Robbie Ray
Pitch: Splitter
Purpose: He wanted to give hitters a different look from his fastball/slider combo.

¡°I think it just gives me something that's just a different dynamic to my game,¡± Ray said. ¡°Everything is kind of hard and goes to my glove side. Ideally it's something that's a little bit softer and goes to my arm side. So I think it just kind of adds another dynamic.¡±

Ray has been a two-pitch pitcher for most of his career, but he added a two-seam fastball mid-start last June in Houston, which became a big weapon for him. In 15 starts against the AL West, he had a 4.16 ERA and opposing hitters had a .264/.323/.492 (.816 OPS) slash line with 18 homers against him, so giving the familiar faces a new look could be part of the logic.

Logan Gilbert
Pitch: Split-changeup
Purpose: He wanted an offspeed pitch that he could trust more.

¡°I've always tried the changeup and just kind of struggled with it, just wasn't natural for me,¡± Gilbert said. ¡°So I¡¯m just trying to find basically a variation of a splitter that I can throw like a fastball.¡±

Because Gilbert has such large hands and huge extension down the mound, the club believes the pitch¡¯s late-breaking movement will be conducive to his profile.?

¡°I kind of thought about it last year and then threw it off some people, and they thought it was a good idea, too,¡± Gilbert said. ¡°I talked to coaches here and then a couple players, and just kind of brainstorming. I'm still developing it, just trying to see what it looks like against hitters.¡±

George Kirby
Pitch: Splitter
Purpose: He wanted something that could induce weak contact.

Last year, only Shohei Ohtani and Chris Bassitt had a more diverse repertoire than Kirby, who threw six different pitches, each one amounting to at least 8 percent of his overall usage. And for a player whose ability to manipulate grips is among the best that his peers have ever seen, why not add a seventh?

¡°I just want something ¡­ more like a heater,¡± Kirby said. ¡°A little more deception, something [with] a little more depth to possibly [induce] a little more swing-and-misses, some weaker contact. ... I kind of just throw it like a heater, and it just falls off the table more vertical. And then I still have my changeup, too, which is a little more horizontal.¡±

Ideally, Kirby said, his split would have an 8-10 mph dropoff from his fastball.

Marco Gonzales
Pitch: Slider
Purpose: He wanted something with more movement than his cutter.

¡°I unintentionally was throwing sliders last year,¡± Gonzales said. ¡°Unintentionally, intentionally. I was trying to make my cutter bigger to lefties and have it kind of run off the plate. This year, I just gave it its own focused path, its own intention, and started calling it a slider and working on it as a slider.¡±

Opposing hitters batted .321 and slugged .547 against Gonzales' cutter last year, per Statcast, which factored into the decision.?

¡°Talking with the pitching coaches, the numbers look good on it,¡± Gonzales said. ¡°So we decided to let it rip. Instead of thinking big cutter, [the slider] is more intentional now.¡±

Chris Flexen
Pitch: Slider
Purpose: He needed a breaking ball.

¡°The curveball for me last year was just a far-below-average pitch,¡± Flexen said. ¡°I just couldn't figure it out. I had a good one in '21. I don't think I'm going to completely get rid of it, but I needed a breaking ball. And when I started working on the slider last year, I had good results with it. I felt good throwing it. So that was the pitch that I wanted to continue to stick with.¡±

Flexen¡¯s curve usage dropped from 15.3 percent in 2021 to 3.6 percent in '22, when opposing hitters had a .615 batting average and 1.308 slugging percentage against it. The slider has shown promise this spring.

¡°Maybe as a starter, if I'm in the rotation or wherever, using the curveball is just kind of a show-me pitch just to say, 'Hey, I still have it,'¡± Flexen said. ¡°But I needed a breaking ball. It was nonexistent for me last year.¡±