Everything Cardinals Fans Need to Know About Eduardo Rivera After Trade with Red Sox

Here is what Cardinals fans need to know about their new left-hander.

Jul 17, 2026; Boston, Massachusetts, USA; Boston Red Sox pitcher Eduardo Rivera (99) pitches during the first inning against the Tampa Bay Rays at Fenway Park. Mandatory Credit: Bob DeChiara-Imagn Images | IMAGN IMAGES via Reuters Connect

Early on Tuesday, the St. Louis Cardinals completed a trade to bring in left-hander Eduardo Rivera from the Boston Red Sox. St. Louis has been working to add more pitching depth to their system, and has found a solid major league ready arm that can be inserted into the rotation in case of an injury.

For Cardinals fans, it may be the first time they have ever heard of Rivera, and they will understandably have questions about their new left-hander. Here is everything that Cardinals fans need to know after the team completed the trade with the Red Sox and brought Rivera in.

Everything to know about Eduardo Rivera

Jul 22, 2026; Boston, Massachusetts, USA; Boston Red Sox pitcher Eduardo Rivera (99) pitches against the Baltimore Orioles during the first inning at Fenway Park. Mandatory Credit: Brian Fluharty-Imagn Images | IMAGN IMAGES via Reuters Connect

Rivera was selected in the 11th round of the 2021 draft by the formerly Oakland Athletics. He was in their minor league system until being signed as a minor league free agent by the Red Sox in June 2024. The big left-hander was ranked Boston's No. 18 prospect entering the 2026 season, and he finally made his major league debut on July 22 against the Baltimore Orioles.

Rivers has averaged 11 strikeouts per nine innings pitched over 267 2/3 innings at the minor league level. he went 7-2 with a 2.59 ERA in five starts and two relief appearances in 2026 before being called up to the major leagues to pitch with the Red Sox.

In three starts and one relief appearance with the Red Sox, the 23-year-old went 0-1 with a 6.30 ERA, though he did not allow a hit to a left-handed batter until his most recent appearance, so there is plenty of upside with him.

More importantly, the Cardinals are getting a major league ready starting pitcher and have strengthened their farm system with more pitching depth. And if an injury takes place, the Cardinals have the option of bringing Rivera up to start a game or two.

He currently is not among the team's top prospects, but he's a good piece to have in the system in case something goes wrong. The Cardinals need to make sure they have enough pitching depth for 2027, and as long as they continue to strengthen it, they should be able to get through the season without too many problems.

It should be interesting to see how the Cardinals go about adding more pitching depth, but this is certainly a good start for a team that was short in that area for a long while.