The Boston Red Sox and St. Louis Cardinals have been frequent trade partners in recent years. And now, the two organizations have agreed to another deal, this time swapping pitching prospects.

Boston traded left-handed pitcher Eduardo Rivera to St. Louis on Tuesday. In return, the Cardinals acquired right-handed pitching prospect Juan Garcia, an 18-year-old who's pitched in 23 Dominican Summer League games over the last two years.

Rivera made his MLB debut this year, tossing 3 1/3 scoreless innings of relief against the New York Yankees. Although the 23-year-old spent most of the 2026 season in Triple-A, he notably appeared in a big-league game before he ever threw a pitch for the Worcester Red Sox. After Tuesday's trade, the southpaw could now have a chance to carve out a role in the Cardinals' 2027 pitching staff.

Outlook on Eduardo Rivera, Juan Garcia heading into next year

In 2026, Rivera posted a 2.59 ERA in 26 minor league games and a 6.30 ERA in four MLB appearances. All but two of the left-hander's minor league outings this year came at Triple-A, where he had a 2.96 ERA and 55 strikeouts in 45 2/3 innings. The Athletics' 11th-round pick in the 2021 MLB Draft has a 3.56 ERA in 89 career minor league appearances.

On the other side of this trade, Garcia heads to the Red Sox after posting a 4.40 ERA in 11 Dominican Summer League starts this year. The 18-year-old has a 3.87 ERA and 77 strikeouts in 90 2/3 innings so far in his professional career. The young right-hander will most likely remain in the lower levels of the minors during his first season in Boston's farm system.

The Red Sox notably included two of their top pitching prospects in the August trade for Baltimore Orioles catcher Adley Rutschman. By sending Rivera to St. Louis, Boston's minor league pitching depth has taken another hit. But now, the southpaw could earn a spot in the big leagues with the Cardinals. It's unclear whether St. Louis plans to use the 6-foot-7 lefty as a starter or reliever, but Cardinals fans should keep an eye on the young hurler early in 2027.