Los Angeles Dodgers officials confirmed on June 4, 2026, they are actively scouting St. Louis Cardinals reliever Riley O’Brien as a possible upgrade in the ongoing MLB Closer Rankings shuffle. This aggressive pursuit intensifies as the trade deadline approaches and the Dodgers find themselves in a precarious position with Edwin Díaz sitting on the injured list. For a franchise that has historically prioritized a “bullpen by committee” approach during the regular season only to pivot toward a dominant anchor for the postseason, the current void at the back end of the relief corps is a glaring liability that Andrew Friedman and the front office are desperate to rectify.
Riley O’Brien, 31, has emerged as one of the most intriguing high-leverage arms in the National League. In 2025, O’Brien posted a 3.95 ERA, allowing 11 earned runs over 48 innings while striking out 112 batters. While the ERA may appear modest at first glance, the underlying peripherals are staggering: O’Brien’s 21.0 K/9 rate was the highest among all relievers with at least 30 innings. This level of dominance suggests a pitcher who does not rely on luck or defensive positioning, but rather a raw ability to miss bats at an elite rate. In the context of the current MLB Closer Rankings, O’Brien represents the modern prototype: a high-velocity arm capable of neutralizing the league’s most dangerous hitters in the eighth and ninth innings.
What does O’Brien’s 2025 performance tell us?
To understand O’Brien’s value, one must look beyond the surface-level ERA. According to Sporting News, O’Brien limited walks to just eight in 48 innings, yielding a 1.5 BB/9 rate, and generated 12.4 strikeouts per nine innings. This combination of extreme strikeout ability and pinpoint control is a rarity in an era where many power arms struggle with command, often leading to high-stress innings and inflated pitch counts.
The secret to O’Brien’s success lies in his arsenal. His sinker‑slider combo spins above 2,400 RPM, a metric highly prized by modern bullpens. The sinker creates significant downward movement that induces ground balls, while the slider serves as a devastating out-pitch with a vertical break that tunnels perfectly with his fastball. This spin rate puts him in the top 5% of all MLB relievers, providing a level of “stuff” that makes him nearly unhittable when he is located. Analysts across the league have noted that O’Brien’s consistency is his greatest asset; unlike many closers who experience volatile swings in performance, O’Brien has maintained a steady strikeout rate regardless of the opponent’s caliber.
From a strategic standpoint, the Dodgers’ analytics department views O’Brien as a force multiplier. Baseball‑Prospectus projects the Dodgers’ bullpen WAR at 2.1 for 2026 without a trade; however, internal modeling suggests that adding O’Brien could raise that figure to roughly 3.0. This increase in Wins Above Replacement isn’t just a statistical curiosity—it represents a tangible difference in the number of games saved and leads preserved. Such an upgrade would likely push O’Brien into the top five of the season’s closer hierarchy, potentially nudging established veterans like Josh Hader and Liam Hendriks down a spot in the MLB Closer Rankings.
How would O’Brien reshape the Dodgers’ bullpen?
The Dodgers have long struggled with the volatility of the ninth inning, often rotating through a series of mid-tier arms who lack the psychological presence of a true “closer.” By acquiring O’Brien, Los Angeles would secure a definitive anchor. The team has already identified a mid‑level prospect and a player to be named later (PTBNL) as potential return pieces for the Cardinals. The specific focus on a mid-level prospect indicates that the Dodgers are willing to sacrifice future depth for immediate stability, a move that mirrors their historical aggression in pursuing championship-caliber pieces.
The front office must now weigh the cost of parting with a prospect against the upside of stabilizing the ninth. The chase underscores how MLB Closer Rankings now drive trade‑deadline narratives more than ever. In the modern game, the “closer’ role has evolved from a simple save-accumulator to a tactical weapon used to neutralize the heart of an opponent’s order. A successful acquisition of O’Brien would signal a shift toward analytics‑driven bullpen construction, where spin rate and K/9 take precedence over traditional save totals.
Historically, the Dodgers have found success when they possess a dominant late-inning presence, such as the eras of Kenley Jansen or the peak of their current high-leverage arms. However, the current void left by Edwin Díaz’s absence has exposed a lack of depth. The Dodgers’ current bullpen has struggled with inherited runners, and the addition of a pitcher with O’Brien’s strikeout capacity would drastically reduce the risk of “blown