Day-To-Day
Injury Calf
2025 Stats
W-L
3-1
ERA
2.06
WHIP
1.15
K
45
SV
6
2026 Projections
2026 Fantasy Outlook
O'Brien opened 2025 in the minors, striking out 32 in 19.1 innings at Triple-A Memphis before he was recalled for his first extended look in the majors. The 30-year-old completed a career-high 48.0 innings for St. Louis, tossing his 98 mph sinker nearly half of the time to suppress hard contact and produce a 54 percent ground ball rate. He didn't strike many batters out and walked more than you'd like to see - his 11.6 K-BB percentage ranked 137th out of the 191 relievers who threw 40-plus innings last year - but the Cardinals' flurry of relief pitcher trades opened up high-leverage opportunities for O'Brien. The right-hander closed out 2025 by racking up four of the last five saves for St. Louis. That puts him in the mix for early 2026 save opportunities, particularly if he throws more curveballs (21 percent pitch usage). O'Brien's curve held opposing hitters to a .059 BA (3rd for that pitch type among those who threw 100+ curveballs) and produced a 50.9 percent whiff rate (4th). Read Past Outlooks
Signed a one-year contract with the Cardinals in March of 2025.
On track for spring debut Friday
O'Brien (calf) is tentatively scheduled to make his Grapefruit League debut Friday against the Orioles, Derrick Goold of the St. Louis Post-Dispatch reports.
Analysis
The right-hander has been slowed in Cardinals camp by a mild right calf strain. O'Brien got through a live batting practice session Monday with no issues, and as long as he bounces back well, he'll get into game action Friday. The hard-throwing O'Brien is competing to open the season as St. Louis' closer.
The right-hander has been slowed in Cardinals camp by a mild right calf strain. O'Brien got through a live batting practice session Monday with no issues, and as long as he bounces back well, he'll get into game action Friday. The hard-throwing O'Brien is competing to open the season as St. Louis' closer.
Pitching Stats
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2025 MLB Game Log
2025
2024
2022
2021
Minor League Game Log
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Pitching Appearances Breakdown
Average Pitch Count
18
Last 10 Games
15
Last 5 Games
14
How many pitches does Riley O'Brien generally throw?
1-10
11-20
21-30
31-40
41-50
51-60
61-70
71-80
81-90
91-100
101-110
111-120
121+
What part of the game does Riley O'Brien generally pitch?
1st
2nd
3rd
4th
5th
6th
7th
8th
9th
Extra
% Games Reaching Innings Threshold
% Games By Number of Innings Pitched
Left/Right Pitching Splits
Since 2023
-18%
BAA vs LHP
2025
-30%
BAA vs LHP
| BAA | K | BB | H | HR | ||||
|---|---|---|---|---|---|---|---|---|
| Since 2023vs Left | .200 | 31 | 13 | 17 | 1 | |||
| Since 2023vs Right | .244 | 25 | 17 | 29 | 3 | |||
| 2025vs Left | .157 | 27 | 9 | 11 | 0 | |||
| 2025vs Right | .224 | 18 | 13 | 22 | 2 | |||
| 2024vs Left | .400 | 4 | 4 | 6 | 1 | |||
| 2024vs Right | .333 | 7 | 4 | 7 | 1 | |||
| 2023vs Left | 0 | 0 | 0 | 0 | 0 | |||
| 2023vs Right | 0 | 0 | 0 | 0 | 0 | |||
| More Splits→ | View More Split Stats | |||||||
Home/Away Pitching Splits
Since 2023
-86%
ERA at Home
2025
-83%
ERA at Home
| ERA | WHIP | IP | K/9 | BB/9 | |||||
|---|---|---|---|---|---|---|---|---|---|
| Since 2023Home | 0.89 | 0.92 | 30.1 | 6.8 | 3.0 | ||||
| Since 2023Away | 6.31 | 1.87 | 25.2 | 11.6 | 7.0 | ||||
| 2025Home | 0.66 | 0.88 | 27.1 | 6.9 | 2.6 | ||||
| 2025Away | 3.92 | 1.50 | 20.2 | 10.5 | 6.1 | ||||
| 2024Home | 3.00 | 1.33 | 3.0 | 6.0 | 6.0 | ||||
| 2024Away | 16.20 | 3.40 | 5.0 | 16.2 | 10.8 | ||||
| 2023Home | 0 | 0 | 0 | 0 | 0 | ||||
| 2023Away | 0 | 0 | 0 | 0 | 0 | ||||
| More Splits→ | View More Split Stats | ||||||||
Stat Review
How does Riley O'Brien compare to other relievers?
This section compares his stats with all relief pitcher seasons from the previous three seasons (minimum 30 innings)*. The bar represents the player's percentile rank. For example, if the bar is halfway across, then the player falls into the 50th percentile for that stat and it would be considered average.
* Exit Velocity, Barrels/BBE %, Balls Hit 95+ MPH %, and Spin Rate are benchmarked against 2019 data (min 30 IP). See here for more exit velocity/barrels stats plus an explanation of current limitations with that data set.
* Exit Velocity, Barrels/BBE %, Balls Hit 95+ MPH %, and Spin Rate are benchmarked against 2019 data (min 30 IP). See here for more exit velocity/barrels stats plus an explanation of current limitations with that data set.
K/BB
2.05K/9
8.4BB/9
4.1HR/9
0.4Fastball
98.0 mphERA
2.06WHIP
1.15BABIP
.255GB/FB
2.64Left On Base
80.5%Exit Velocity
80.7 mphBarrels/BBE
2.4%Spin Rate
2299 rpmBalls Hit 95+ MPH
21.5%Swinging Strike
10.8%Advanced Pitching Stats
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Defensive Stats
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Stats Vs Today's Lineup
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More Fantasy News
Bullpen session Tuesday
O'Brien (calf) is scheduled to throw a bullpen session Tuesday, Jeff Jones of the Belleville News-Democrat reports.
Analysis
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Out for WBC with mild calf strain
Cardinals manager Oliver Marmol said Friday that O'Brien will be shut down for a few days due to a mild right calf strain, Brian Murphy of MLB.com reports.
Analysis
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Nursing sore calf
O'Brien is managing calf soreness that is being evaluated Tuesday, Jeff Jones of the Belleville News-Democrat reports.
Analysis
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Snags save Tuesday
O'Brien struck out the only batter he faced to earn the save in Tuesday's 9-8 win over the Giants.
Analysis
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Notches save No. 5
O'Brien picked up the save in Tuesday's 3-0 win against the Reds, striking out one in a perfect ninth inning.
Analysis
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Latest Fantasy Rumors
Eligible for promotion Monday
O'Brien will be eligible to be recalled by the Cardinals on Monday, and Jeff Jones of the Belleville News-Democrat speculates the right-hander could be called up from Triple-A Memphis at some point this week.
Analysis
O'Brien could have joined the Cardinals over the past couple weeks if the corresponding move was an IL transaction, but he's stayed a Triple-A for the full 15 days. The 29-year-old has made just one appearance in the majors this season but has been dominant in 13 outings for Memphis with a 1.46 ERA, 0.99 WHIP and 9:5 K:BB over 12.1 innings.
O'Brien could have joined the Cardinals over the past couple weeks if the corresponding move was an IL transaction, but he's stayed a Triple-A for the full 15 days. The 29-year-old has made just one appearance in the majors this season but has been dominant in 13 outings for Memphis with a 1.46 ERA, 0.99 WHIP and 9:5 K:BB over 12.1 innings.