Athletics? Giants? 3 Best MLB Free Agent Fits for D-backs RHP Zac Gallen

The dust has mostly settled on the MLB free agent market, but a handful of impactful players are still for the taking, most notably Arizona Diamondbacks right-hander Zac Gallen. While the 30-year-old Gallen is coming off a 2025 season that saw him post a career-high 4.83 ERA, he has been among the best starting pitchers in the sport for the better part of his MLB career (2019-present) and is a proven top-of-the-rotation force; he can move the needle for a pitching staff that needs a boost. Here are the top three fits for Gallen should he depart Arizona. Baltimore Orioles Since losing Corbin Burnes last offseason, the Orioles have been searching for an ace. Adding Gallen would, at the very least, quell some of the concern about the upper portion of Baltimore's rotation. Gallen would beef up an Orioles' starting rotation that was 26th in MLB in opponent batting average (.265), 24th in ERA (4.65) and 21st in WHIP (1.32) last season. The right-hander, who leans on his four-seamer and knuckle curve while mixing in a changeup, pitches deep into games and was the ace of Arizona's starting rotation en route to it winning the 2023 National League pennant. Combine Gallen with left-hander Trevor Rogers, who posted a 1.81 ERA and 5.5 wins above replacement in 18 starts last season, and offseason acquisition Shane Baz, among others, and the Orioles would have a plausible rotation. Plus, with the additions of star first baseman Pete Alonso and outfielder Taylor Ward — who blasted a career-high 36 home runs last season — an improved starting staff gives the Orioles a chance to compete in an ever-improving American League East. That said, given that Baltimore has already made some moves on the pitching front this offseason (trading for Baz and re-signing Zach Eflin), it may prefer to add a more consistent ace-caliber pitcher like Framber Valdez or make a blockbuster trade (e.g., acquiring Detroit Tigers two-time Cy Young Award winner Tarik Skubal), rather than take a chance on Gallen getting back on track should it seek to add another starting pitcher. San Francisco Giants The Giants are in no man's land in the National League West (the Los Angeles Dodgers and San Diego Padres are in their division), but they have plenty of potent talent and should be operating as if they expect to be in the postseason. Operating as such entails adding to their starting rotation, and signing Gallen would fit the bill. From 2022-24, Gallen averaged a 3.20 ERA and 1.09 WHIP per season with the Diamondbacks. He can post strikeouts at an efficient rate and would improve a Giants' starting rotation that was tied for 23rd in WHIP (1.34), tied for 23rd in opponent batting average (.255) and was 17th in ERA (4.10) last season. Sure, the Giants have already added veteran right-handers Tyler Mahle and Adrian Houser this offseason. At the same time, assembling a rotation trio of Logan Webb, Robbie Ray and Gallen would make for a fierce attack. That's without mentioning that Mahle posted a 2.18 ERA in 16 regular-season starts for the Texas Rangers last season, right-hander Landen Roupp has held his own to date (3.80 ERA in 22 starts last season) and Houser is a proven commodity who can also come out of the bullpen. The Giants have been both buyers (signing Willy Adames on a seven-year, $182 million deal and acquiring Boston Red Sox star infielder Rafael Devers) and sellers (they traded relievers Camilo Doval and Tyler Rogers and outfielder Mike Yastrzemski at the 2025 MLB trade deadline) over the last 18 months. Combining it all, though, this team is closer to competing for the playoffs than hoping to win the MLB Draft Lottery (that's still funky to type out). Adding Gallen gives the Giants a fighting chance. At the same time, while Gallen would enhance San Francisco's chances of returning to the postseason, he could progress a different California team in a more profound way. Athletics The Athletics are close, and with an improved starting rotation, they have a legitimate chance of being a playoff team next season, hence them being a fit for Gallen. Why are the A's, who won 76 games last season, "close?" Outside of teams that made the playoffs in 2025, the A's have the best young positional core in baseball, which includes Nick Kurtz, Tyler Soderstrom, Jacob Wilson, Shea Langeliers and Lawrence Butler. It's also a unit that's complemented by two-time All-Star Brent Rooker and could later be joined by highly touted infield prospect Leo De Vries, who was acquired in a 2025 trade with the Padres. Last season, the Athletics' offense was tied with the Philadelphia Phillies for fourth in slugging percentage (.431), while being fifth in hits (1,403) and tied for fifth in batting average (.253). What was this offense accompanied by? A starting rotation that was 27th in ERA (4.85), 25th in opponent batting average (.257) and tied for 23rd in WHIP (1.34). Gallen would become the Athletics' ace from the outset, providing a stabilizing right-hander with postseason experience who's in the prime of his career to anchor their pitching staff. The need for a top-of-the-rotation arm, if not two, comes with the continued struggles of the A's to develop their homegrown pitchers into rotation linchpins. Meanwhile, free agent signee Luis Severino had a rough first year with the team in 2025 (4.54 ERA in 29 starts), while left-hander Jeffrey Springs (4.11 ERA in 32 appearances/30 starts) was arguably their best starting pitcher. With Gallen in the fold, the urgency for Jacob Lopez, J.T. Ginn, Luis Morales and a healthy Gunnar Hoglund, among other young pitchers, to make a jump would decrease. Gallen's timeline and that of the burgeoning A's is a match.