Seattle Mariners president of baseball operations Jerry DiPoto spent time with the Arizona Diamondbacks in the early 2000s, ascending to the role of general manager in 2010. Though he's since moved north, the Mariners and Diamondbacks have become frequent trade partners over the past few years.
With the 2025 MLB trade deadline approaching, that could be something to monitor, according to MLB Network's Jon Morosi.
Quoting one of his own posts on X about Zac Gallen's second straight strong outing for Arizona, Morosi speculated that the former All-Star could be on the move.
“The Mariners and DBacks are frequent trade partners, with 5 deals involving major league players since Jerry Dipoto arrived in Seattle,” he wrote. “If the M’s need an arm, this is one scenario that could develop closer to the deadline.”
Gallen hasn't exactly put up appealing numbers for the Diamondbacks this year, going 7-9 with a 5.15 ERA. He also has a career-high WHIP (1.345) and career low strikeout rate (22.7%). But as Morosi said, his last two starts have been stellar. In that time, he's thrown 13 innings, giving up just 10 hits and one earned run while striking out 19.
The Mariners have trade deadline needs beyond their rotation

The Mariners rank middle-of-the-pack in team starting pitching by ERA (14th) and strikeouts (11th). With Bryan Woo and Luis Castillo at the front end, Seattle doesn't need to go all-in on improving the rotation.
Instead, they could focus on weak spots of their lineup, where there should be plenty of available options. As a team, they rank 12th in team OPS despite Cal Raleigh's historic home run pace. Meanwhile the Baltimore Orioles could make Ryan O'Hearn available. As someone who has played right field and first base this year, he can fill two areas of need.
O'Hearn is hitting for a career-high .839 OPS, thanks to a .287 average, 11 home runs and his best walk rate since 2020.
If DiPoto wants to work his Diamondbacks magic, however, third baseman Eugenio Suarez and his 28 home runs could also be a fit. That is, of course, assuming Arizona is a deadline seller. The Diamondbacks are a game under .500 but also only 4.5 games out of the Wild Card, so they can go either way.