The Seattle Mariners would be the first team I'd call regarding starting pitchers if I were Mike Hazen. The Mariners have so many starting pitchers they're not going to know what to do with all of them. While there's no such thing as enough pitching depth, the M's have a ridiculous amount of starters and it would be wasteful just to hoard them in the name of depth alone.
Their rotation is headed by a big three of Logan Gilbert, Luis Castillo, and George Kirby, one of the most intimidating 1-3s in baseball. After that, they have plenty of young options like Bryce Miller, Bryan Woo, Emerson Hancock, and veteran Marco Gonzales. Plus, Robbie Ray, the 2021 Cy Young winner, will likely return near summertime, as long as there are no setbacks in Tommy John surgery.
When healthy, Gonzales can be a durable and quality starting pitcher. From 2018 to 2022, Gonzales pitched 765.1 innings, the 11th most in baseball, with a 104 ERA+. Last year, however, he only managed to play in 11 games with a poor 5.22 ERA/78 ERA+. Granted, his 4.28 FIP is par for the course for him. With two years of control left, Marco will likely be the first player the M's shop.
You could also see a prospect-for-prospect swap, including one of the D-Backs' many outfield prospects for one of the M's young pitchers. There definitely is a possibility between a Mariners and Diamondbacks swap, simply given the amount of pitching depth Seattle has at their disposal.