St. Louis Cardinals Closer Riley O’Brien

High level – the results

Off to the left we see Riley’s current season Statcast page. A sea of red. Always a good thing. Without sharing last year’s image with you, I can tell you he has improved Chase%, Whiff% and K% and BB% from 2025 to 2026. All but the Whiff% are now in the elite zone. What is not to like? One might not care for the below average run value of the off-speed pitches. For the record, he has thrown 2 of those pitches this year (changeups). So, ignore that.

The pitch mix

Down below, you can see the pitches Riley has used and how they get allocated. 58% sinker (who wouldn’t?) averaging 98.3 mph. Note that the sinker has higher than average drop. As in about 10% more drop that MLB average and also about 10% more ride (in on RH batters).

Pitch Shapes

To go another layer deep, let’s look at the movement profiles of these pitches.

Deception

A key for a pitcher is to be able to disguise their pitches, which they do a number of ways. One of the most looked at is spin direction. Really sharp-eyed hitters can detect the direction of the ball’s spin. Some spin angles look like red dots (the seams) while other look more like a fan. In Riley’s case, his two best pitches (SI and ST) have the exact opposite spin direction, meaning the hitter won’t see a difference. By the time a RH hitter detects whether the ball is riding in on him (SI) or floating away (ST), it’s hard to adjust, especially with the velo difference between the two. Part of his success is how these two pitches play off each other.

How the stuff plays

No charts, but some data points. Riley has showed improvement in Stuff+ 4 years running. Last year he was 106, this year 110. That is the look of a pitcher refining, not making leaps. His Location+ has followed the same general trend. Last year, Location+ was commendable 107 and this year has risen to 118. While a 1.5% walk rate is probably not where he will end the year, these numbers suggest his command is not fluky, either. Historically, O’Brien’s big bugaboo has been walking batters. His 2026 walk rate is currently at an unsustainable 1.5%. BB% rates don’t stabilize until closer to mid-year, so this will be one area where we can expect regression. His K% rate is 28.4% (good) and has reached the stabilization level I referenced earlier. Looking at his career, he could regress a bit, but unlikely to move too much.

The future

If Riley O’Brien was 25 years old, we’d be looking at a long-term closer gig ala. Helsley. But he is not. He is 31 years old, presumably on the downward side of the aging curve. While he has six years of team control (2025 included), he is unlikely to be a long-term closer here (or anywhere). But short-term? Come the trade deadline, the Cardinals are going to have an interesting choice to make. Closers, especially elite ones, tend to command a handsome dowry around Aug 1. If you look into the Cardinals pipeline, there are a few guys in that line that have “reliever risk” attached to their name, and closer stuff on their Prospect Savant page. Will the remaining control make him valuable to the Cardinals upcoming window of contention? Or will his age and the burgeoning pitching make him expendable? Almost with certainty, they will ask for and require a king’s ransom to move a player with the kind of stuff and control he has. I would tend to think last year’s Mason Miller trade might be a decent guidepost and if I remember, that took a #1 prospect (De Vries) to pry him off the A’s roster. That might be a little rich for some teams, but probably not much less than would be needed to move him. Bloom is in a win-win with this one.