SEATTLE, WA - MAY 27: Starter Luis Castillo #58 of the Seattle Mariners celebrates after a striking out Carlos Santana #41 of the Pittsburgh Pirates to end the top half of the sixth inning of a game at T-Mobile Park on May 27, 2023 in Seattle, Washington. (Photo by Stephen Brashear/Getty Images) | Getty ImagesWhen Castillo was brought in at the 2022 trade deadline, my whole perspective on this franchise shifted. Riding a 14-game winning streak, the Mariners found themselves in a playoff spot at the deadline. It was time. A top-10 prospect and a top-50 prospect plus two depth pieces was a high price, but I was sure Castillo was worth it. And for as good as Castillo was, its hard to overstate how much that trade meant. It was a signal about who the Mariners were as a franchise. They were in it for real.And as for the man himself, I was smitten right away. Meeting up with the team in New York, Castillo dyed the end of his hair teal and blue to replace the Cincinnati Red. He was all in. He struck out 8 Yankees over 6.2 innings, picking up the first of his 43 wins in a Mariners uniform. The fact that the Mariners had outbid the Yankees to get Castillo only sweetened the moment, underlining Castillos meaning. He followed that up in his first home start at T-Mobile by facing the Yankees again, pitching eight shutout innings in the best game Ive ever seen. Those were the first two of 11 starts he ripped off to close out 2022 with a 3.17 ERA and a strikeout rate of 28.9%.On a team that lacked a frontline starter, he was the obvious choice to start Game 1 of the Wild Card Round. The only swear word in the Sun Hat Award record book refers to why he won the award that day: for kicking the shit out of the Blue Jays in Seattles first postseason game in 21 years. His final line that day? 7.1 IP, 0 R, 6 H, 5 K, 0 BB, 19 whiffs. He averagedaveraged100 mph on both his four-seamer and his two-seamer. Luis Castillo was the proof. The Mariners had arrived.He followed that up with an All-Star 2023. His final numbers belie how elite that season was. He pitched at least five innings in 32 of his 33 starts, living up to his La Piedra nickname. His 3.01 ERA and K-BB% of 21.8% through August had him entering the seasons final month in the pole position for the Cy Young Award.Along the way, he was always the showman, even helping keep things light through the teams struggles, using his signature flex to joke around with Shohei Ohtani. And he fought to keep the team in the running, collecting 22 whiffs in the game that saw his 1,000th career strikeout. It was a season that saw the MLB debuts of Bryce Miller, Bryan Woo, and Emerson Hancock. Certainly each of them was impressive as a rookie, but its easy to forget in retrospect how much they struggled and how much it mattered that Castillo was there to keep the ship steady.As the team scuffled through 2024, Castillo was a shining beacon of competence. He was a key part of the rotations stretch of 21 consecutive games allowing 2 runs or fewer. One of those starts was his nine-strikeout dismantling of the Rockies as the snow fell in the Denver night, smacking down all the talk about how hes a hot-weather pitcher.It was the first year of his decline, but he was making adjustments to keep making it work, including a mid-game adjustment in a game against Anaheim to complete a sweep. That was one of several games when his fastest pitch of the night was his last one. Emptying the tank at the end is just one of many stratagems he shared with his rotationmates that helped them ascend to their own stardom.Castillos arrival really signaled something about the franchise. And if all he did was anchor the 2022 stretch run, that would have been enough. But as the years passed by, his legacy came into clearer focus. From the time Bryan Woo replaced Marco Gonzales in June 2023, this rotation belonged to Castillo. Yesterday, Logan Gilbert told Angie Mentink, Luis [always] told me after a bad outing, dont change anything. You dont need to change anything. La Piedra was such a steady, level-headed presence that he could even get that message through to his most neurotic teammate. Gilbert reports that after one particularly bad bullpen outing, He told me, Dont think too much, dont change too much, dont try too hard. . . . He knew the right words to say at the right time. He was always that way.Last year, the Mariners entered the season with the rotation as the unquestioned strength of the team, practically its whole identity. But while it was a strength, the starters struggled to stay on the field. Castillo was the only pitcher to make each and every one of his scheduled starts. Though he was no longer the front man of the rotation, he remained the rock. In that way, he was the man who led this franchise to its first division title in a quarter century. Its no wonder he was on the mound the night they clinched that title, striking out 10 over 7.1 innings of one-hit ball.Age comes for us all, and rosters turn over. Luis Castillo was the veteran who steadied the young team, and now the time has come for him to help shepherd another young team. The Mariners rotation is five home-grown grown-ups now. But they grew up under Luis Castillo, and thats a mark that wont be forgotten. When the Mariners celebrate their 100th season, hell be in the video highlights.Before todays game, Andrs Muoz said, Today is a sad day. I couldnt agree more. Castillo was a giant, and he gets a rare off-recap Sun Hat Award, his fifth and final one, in honor of his four years of exceptional service to the franchise, to the fan base, and to me. Gracias, La Piedra. La Piedra Para Siempre.