His fastball is the pitch everything else is built on
O'Brien's sinker averages 97.7 mph, and has touched 101.1.
622 thrown, 58.5% of his pitches.
When he falls behind, hitters know exactly what is coming
Behind in the count O'Brien throws a fastball 74.7% of the time, against 42.1% when he is ahead.
269 pitches behind in the count, 330 ahead.
This is the pitch he goes to when he needs the out
With two strikes O'Brien goes to the sweeper: 45.9% of his two-strike pitches, against 26.7% the rest of the time.
340 two-strike pitches in 2026.
One pitch of his runs sideways more than almost anyone's
O'Brien's sinker moves 16.1 inches toward the third-base side, the biggest horizontal move in his arsenal.
622 thrown, averaging 97.7 mph.
He throws about as hard as anybody in the league
O'Brien averages 93.3 mph across his arsenal, 92nd percentile in the league.
337 pitches in 2026. 92nd percentile among qualified pitchers in 2026, 44th in MLB.
He works one part of the zone far more than the rest
O'Brien lives at the bottom of the zone: his average pitch crosses at 2.06 feet, against a zone that runs 1.5 to 3.5.
1061 located pitches in 2026.
There is one pitch of his that keeps getting hit
Contact off O'Brien's slider leaves the bat at 92.3 mph, against 84.4 off his sweeper.
82 and 349 of them thrown.
He throws strikes to one type of hitter and not the other
O'Brien lands 52.6% of his fastballs in the zone and only 28.3% of his breaking balls.
196 of his fastballs, 139 of his breaking balls.
The angle he throws from is unusual, and hitters notice
O'Brien releases the ball from a low three-quarters slot, about 34 degrees above horizontal and 1.6 feet to the third-base side of the rubber.
1061 tracked release points, averaging 5.5 feet off the ground.
The gap between his pitches is what makes them work
14.9 mph separates O'Brien's sinker from his sweeper, 97.7 against 82.9.
622 and 349 of them respectively.
He pitches around the zone once runners are on
O'Brien throws 38.4% of his pitches in the zone with a runner in scoring position and 43.3% with the bases empty.
73 pitches with a runner in scoring position, 264 with the bases empty.
His pitches move in ways that fit together
O'Brien works with 3 pitches: Sinker, Sweeper and Slider. The sinker is 58.5% of everything he throws.
1064 classified pitches in 2026.
One type of hitter does all the damage against him
Hitters do their damage on his fastballs: a .320 expected average against them, against .268 on his breaking balls.
196 of his fastballs thrown.
How much of the zone he uses depends on the count
O'Brien puts 53.9% of his pitches in the zone when he is behind and 34.3% when he is ahead.
269 located pitches behind, 327 ahead.
Hitters cannot square him up, the contact is weak
Contact against O'Brien is weak: 86.7 mph off the bat on average, 74th percentile.
337 pitches in 2026. 74th percentile among qualified pitchers in 2026, 140th in MLB.
He lives on one side of the plate
O'Brien works in on right-handers: his average pitch lands 2.2 inches to that side of the middle of the plate.
1061 located pitches in 2026.
He gets so far down the mound the ball arrives early
O'Brien releases the ball 6.8 feet down the mound, so the ball arrives sooner than the radar gun suggests.
978 tracked pitches in 2026.
He gets ahead early and pitches from in front all night
O'Brien throws a strike on the first pitch 64.5% of the time.
276 plate appearances started in 2026.
One pitch of his spins more than almost anyone's
O'Brien's slider spins at 2,444 rpm, the highest in his arsenal.
82 thrown in 2026.
The contact he allows should not turn into many hits
The quality of contact against O'Brien projects a .310 average, 64th percentile.
337 pitches in 2026. 64th percentile among qualified pitchers in 2026, 192nd in MLB.
He saves one pitch for one side of the plate
O'Brien throws the slider 12.2% of the time against left-handers and 2.9% against right-handers.
515 pitches to right-handers, 549 to left-handers.
One pitch exists only to make the hitter think
O'Brien has thrown 11 changeups this season, 1% of his pitches, at 90.9 mph: a look rather than a weapon.
1064 classified pitches in 2026.
Show more
The numbers behind these live in Pitch Data.
Take me there
His fastball is the pitch everything else is built on
O'Brien's sinker averages 97.7 mph, and has touched 101.1.
622 thrown, 58.5% of his pitches.
There is one pitch of his that keeps getting hit
Contact off O'Brien's slider leaves the bat at 92.3 mph, against 84.4 off his sweeper.
82 and 349 of them thrown.
The gap between his pitches is what makes them work
14.9 mph separates O'Brien's sinker from his sweeper, 97.7 against 82.9.
622 and 349 of them respectively.
His pitches move in ways that fit together
O'Brien works with 3 pitches: Sinker, Sweeper and Slider. The sinker is 58.5% of everything he throws.
1064 classified pitches in 2026.
One pitch of his spins more than almost anyone's
O'Brien's slider spins at 2,444 rpm, the highest in his arsenal.
82 thrown in 2026.
He saves one pitch for one side of the plate
O'Brien throws the slider 12.2% of the time against left-handers and 2.9% against right-handers.
515 pitches to right-handers, 549 to left-handers.
One pitch exists only to make the hitter think
O'Brien has thrown 11 changeups this season, 1% of his pitches, at 90.9 mph: a look rather than a weapon.
1064 classified pitches in 2026.
Show more
The numbers behind these live in Pitch Data.
Take me there
When he falls behind, hitters know exactly what is coming
Behind in the count O'Brien throws a fastball 74.7% of the time, against 42.1% when he is ahead.
269 pitches behind in the count, 330 ahead.
This is the pitch he goes to when he needs the out
With two strikes O'Brien goes to the sweeper: 45.9% of his two-strike pitches, against 26.7% the rest of the time.
340 two-strike pitches in 2026.
How much of the zone he uses depends on the count
O'Brien puts 53.9% of his pitches in the zone when he is behind and 34.3% when he is ahead.
269 located pitches behind, 327 ahead.
He gets ahead early and pitches from in front all night
O'Brien throws a strike on the first pitch 64.5% of the time.
276 plate appearances started in 2026.
The numbers behind these live in Pitch Data.
Take me there
One pitch of his runs sideways more than almost anyone's
O'Brien's sinker moves 16.1 inches toward the third-base side, the biggest horizontal move in his arsenal.
622 thrown, averaging 97.7 mph.
The numbers behind these live in Pitch Data.
Take me there
He throws about as hard as anybody in the league
O'Brien averages 93.3 mph across his arsenal, 92nd percentile in the league.
337 pitches in 2026. 92nd percentile among qualified pitchers in 2026, 44th in MLB.
The numbers behind these live in Pitch Data.
Take me there
He works one part of the zone far more than the rest
O'Brien lives at the bottom of the zone: his average pitch crosses at 2.06 feet, against a zone that runs 1.5 to 3.5.
1061 located pitches in 2026.
He lives on one side of the plate
O'Brien works in on right-handers: his average pitch lands 2.2 inches to that side of the middle of the plate.
1061 located pitches in 2026.
The numbers behind these live in Pitch Data.
Take me there
He throws strikes to one type of hitter and not the other
O'Brien lands 52.6% of his fastballs in the zone and only 28.3% of his breaking balls.
196 of his fastballs, 139 of his breaking balls.
One type of hitter does all the damage against him
Hitters do their damage on his fastballs: a .320 expected average against them, against .268 on his breaking balls.
196 of his fastballs thrown.
The numbers behind these live in Pitch Data.
Take me there
The angle he throws from is unusual, and hitters notice
O'Brien releases the ball from a low three-quarters slot, about 34 degrees above horizontal and 1.6 feet to the third-base side of the rubber.
1061 tracked release points, averaging 5.5 feet off the ground.
He gets so far down the mound the ball arrives early
O'Brien releases the ball 6.8 feet down the mound, so the ball arrives sooner than the radar gun suggests.
978 tracked pitches in 2026.
The numbers behind these live in Matchups.
Take me there
He pitches around the zone once runners are on
O'Brien throws 38.4% of his pitches in the zone with a runner in scoring position and 43.3% with the bases empty.
73 pitches with a runner in scoring position, 264 with the bases empty.
The numbers behind these live in Spray Chart.
Take me there
Hitters cannot square him up, the contact is weak
Contact against O'Brien is weak: 86.7 mph off the bat on average, 74th percentile.
337 pitches in 2026. 74th percentile among qualified pitchers in 2026, 140th in MLB.
The contact he allows should not turn into many hits
The quality of contact against O'Brien projects a .310 average, 64th percentile.
337 pitches in 2026. 64th percentile among qualified pitchers in 2026, 192nd in MLB.
Cardinals