We already knew that St. Louis Cardinals catcher Ivan Herrera was likely to miss the World Baseball Classic because of insurance issues.

Now it appears that another member of the Cardinals will miss the WBC and stay back with the team in Jupiter, Fla.: Relief pitcher Riley O'Brien.

We heard that O'Brien was dealing with calf soreness on Tuesday and evidently that soreness is going to keep him out of the WBC, where he was scheduled to represent Korea. It was going to be his first time playing in the international tournament. 

The popular KBO in English account on social media says that O'Brien has already been replaced from the roster.

BREAKING

Doosan Bears star CL Kim Taek-yeon will be added to Team Korea’s roster replacing injured RHP Riley O’Brien of the St. Louis Cardinals

Now 30 years old, O'Brien has spent parts of four years in the big leagues with the Cincinnati Reds, Seattle Mariners and Cardinals, but he really broke out for St. Louis in 2025.

One of the bright spots of the Cardinals roster that finished fourth in the National League Central, O'Brien made 42 big-league appearances last season, going 3-1 with a 2.06 ERA. He struck out 45 batters in 48.0 innings, registering six saves. He also made 19 appearances for Triple-A Memphis, going 1-0 with a 2.79 ERA.

He seems to have the stuff to be the team's closer, but he'll have to battle it out with JoJo Romero and Ryne Stanek for the job. The question now is how this injury factors into that battle. Is this calf going to give him a problem for long enough for those two to move ahead of him on the depth chart?

Even if that's the case, O'Brien will feature prominently in Oli Marmol's bullpen. Both Stanek and Romero could be traded before the end of the season so O'Brien could end up as the closer regardless.

--The Cardinals spoke about the plan for switch-pitcher Jurrangelo Cijtnje this season on Wednesday. A Top 100 prospect according to some services, the Cardinals acquired Cijntje from the Seattle Mariners in the Brendan Donovan trade earlier this offseason. 

--Speaking of Herrera, the Cardinals are evidently working on his positional flexibility heading into 2026. A catcher by trade, Herrera was seen taking outfield reps earlier this week. Other Cardinals catchers worked out at first base on Wednesday.

Remember to join our CARDINALS on ROUNDTABLE community, which is FREE! You can post your own thoughts, in text or video form, and you can engage with our Roundtable staff, as well as other CARDINALS fans. If prompted to download the Roundtable APP, that's free too!