MLB Trade Rumors: Braves Land Luis Castillo in Proposed Trade

The Atlanta Braves have some injuries to deal with on their starting staff this season. Spencer Schwellenbach and Hurston Waldrep are out until about June, and others are coming back from injury.

Landing another big-time ace would be a huge boost to the Atlanta rotation for 2026.

With that, we'll have a look at a trade proposal from Sports Illustrated’s Duke Demmings that would bring Seattle Mariners ace Luis Castillo to Atlanta.

Atlanta Braves receive:

SP Luis Castillo

Seattle Mariners receive:

C Sean Murphy
SP Owen Murphy (Braves No. 6 prospect)

Castillo would immediately be the No. 2 starter on the Braves, behind Chris Sale. Spencer Strider is supposed to hold that role, but after an unimpressive comeback season from Tommy John surgery last year, he's started the Grapefruit League schedule with a 6.23 ERA over 4.1 innings. After a 4.45 ERA last year and a 1.40 WHIP, there's no guarantee he will be a top-of-the-rotation arm in 2026.

Which makes a potential acquisition of Castillo that much more important.

The 33-year-old Mariners right-hander had another strong season in 2025, with a 3.54 ERA, 1.18 WHIP, and a 162:46 strikeout to walk ratio. He's maintained an ERA in the mid-3s since coming over to Seattle three+ years ago.

The Braves can afford to give up Sean Murphy in this hypothetical deal, as Drake Baldwin burst onto the scene last season as the starting catcher, winning NL Rookie of the Year honors.

For the M's, their catching situation is obviously in good hands with 60-HR man Cal Raleigh. But Murphy could serve as more of a DH, which could keep him healthier. He missed 70 games last season and over 100 the year before due to injuries. He still managed to launch 16 homers in 291 at-bats in 2025, though he batted just .199. He was an All-Star in 2023 in his first year in Atlanta, with 21 long balls and an .844 OPS. If he's healthy (which he isn't expected to be before early May), he could return to a better performance at the plate, as long as he doesn't have to squat behind it very often.

The other Murphy in this mock deal going to Seattle is a young pitching prospect who's ranked 6th on the Braves' top prospects list. The 22-year-old will start the year in Double-A, and "he has all the ingredients to develop into a big league starter", per MLB Pipeline.

The Atlanta rotation is a whole lotta question marks this season, and they could sure use a consistent workhorse arm like Castillo.