First-Time All-Star and Early Dominance
The St. Louis Cardinals finished the 2026 season with a 77-85 record, missing the postseason for the first time since 2022. Despite the team's overall performance, reliever Riley O'Brien emerged as a standout performer, earning his first All-Star selection and becoming the only Cardinals pitcher named to the 2026 National League All-Star team.
During the first half of the 2026 season, O'Brien demonstrated significant effectiveness on the mound. He posted a 3.43 earned run average over 37.1 innings, striking out 39 batters. His reliability in high-leverage situations was evident as he converted 24 of 28 save opportunities.
His total of 24 saves in the first half ranked as the second-most in the National League, trailing only Mason Miller's 25 saves. This early success established O'Brien as a primary candidate for the closer role heading into the second half of the season.
Pitching Adjustments and All-Star Appearance
O'Brien's performance in the first half was supported by notable adjustments to his pitch selection. In 2026, he reversed his previous usage patterns for breaking balls, lowering his slider usage to just over 7 percent compared to more than 30 percent in 2025.
His prominence during this stretch led to his selection for the 2026 All-Star Game. During the game, O'Brien pitched a scoreless inning. However, the appearance included an incident where he hit Tampa Bay Rays third baseman Junior Caminero with a fastball.
Second-Half Decline and Late-Season Struggles
O'Brien's effectiveness declined significantly in the second half of the 2026 season. Across 27 games, he posted a 5.11 earned run average, recorded 25 strikeouts, and walked 14.4 percent of batters faced.
The shift in performance coincided with a specific date late in the season. O'Brien's numbers declined notably after August 23, when he entered to close out a game against the Philadelphia Phillies.
Looking Ahead to 2027
The stark contrast between O'Brien's first-half dominance and his second-half struggles leaves questions regarding his role for the upcoming season. The Cardinals' failure to reach the postseason in 2026, their first miss since 2022, adds pressure to roster decisions.
As the team looks toward 2027, O'Brien's ability to maintain the pitch adjustments that helped him succeed early in the year will be a key factor in determining whether he retains the closer position.