Sal Stewart's RBI Title Odds Cross 52% as Alvarez's Triple Crown Bid

Sal Stewart of the Cincinnati Reds leads Major League Baseball with 104 RBIs as of August 31, 2026, and prediction markets on the Pro Baseball RBIs Leader event now give him a 52% implied probability of finishing the season on top. That number has climbed 18 percentage points in three days, the largest short-window move this market has recorded. Yet 52% is barely better than a coin flip, and the reason the market refuses to price Stewart any higher has a name: Yordan Alvarez.

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Sal Stewart Leads MLB With 104 RBIs and Now Holds a 52% Chance of Winning the RBI Title

Stewart became the first rookie since Pete Alonso in 2019 to reach 100 RBIs on August 28. Two days later, he launched his 30th home run of the season, joining Hall of Famer Frank Robinson as the only Reds rookies to post a 30-homer, 100-RBI campaign. Those milestones coincided with a sharp repricing across both Kalshi (47%) and Polymarket (56%), pushing the blended probability to 52%.

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The nine-point gap between Kalshi and Polymarket is notable. Polymarket bettors are pricing Stewart at 56%, while Kalshi lags at 47%. That spread suggests the two platforms are processing the same information at different speeds, or that each venue's participant base weighs the Alvarez threat differently. Either way, the composite 52% reflects a market that sees Stewart as the frontrunner but not the presumptive winner.

One month of regular-season baseball remains before the September 28 resolution date. Stewart's 104 RBIs put him on pace for roughly 120 by season's end, a total that would be the highest by any player since Freddie Freeman's 121 in 2023. The question is whether pace alone can withstand a rival chasing something far bigger than a single counting stat.

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Yordan Alvarez's Triple Crown Bid Is the Reason Sal Stewart Isn't a Heavy Favorite

Alvarez entered August slashing .329/.442/.640 with 35 home runs and 85 RBIs, leading the majors in both batting average and home runs while sitting within striking distance of the RBI lead. The gap between Alvarez and Stewart stood at roughly 19 RBIs entering September. That deficit looks steep until you consider what Alvarez is playing for.

No player has won the MLB Triple Crown since Mickey Mantle in 1956. Only four players have ever led the entire majors (not just one league) in average, home runs, and RBIs in the same season: Mantle, Ted Williams (1942), Lou Gehrig (1934), and Rogers Hornsby (1925). Alvarez is alive in all three categories. That distinction creates a structural incentive that extends beyond Alvarez himself. Houston's front office, its lineup construction, and the Astros' September schedule all tilt toward maximizing Alvarez's plate appearances in high-RBI situations.

Triple Crown contenders in the final month historically benefit from lineup protection and intentional sequencing. Managers bat their star cleanup hitter behind runners more aggressively when a generational milestone is within reach. Alvarez doesn't need to sustain an unrealistic pace to close a 19-RBI gap. He needs roughly five more RBIs per week than Stewart over four weeks, a deficit that narrows quickly if Alvarez stays hot and Stewart encounters even a brief slump.

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What Drove Sal Stewart's Odds From 34% to 52%, and Whether the Move Is Justified

The 18-point surge over three days represents a dramatic reversal. As recently as August 25, Stewart's implied probability had fallen to 24%, even though he held a one-RBI lead over Alec Burleson at the time. That earlier decline suggested the market was skeptical of Stewart's ability to maintain his lead through September. What changed?

The timing aligns with Stewart's milestone stretch: 100 RBIs on August 28, 30 home runs on August 30, and a widening gap over every challenger except Alvarez. No single catalyst from the past 72 hours has been confirmed as the specific trigger, but the accumulation of Stewart pulling away from the field (with Alvarez as the lone exception) likely drove the repricing. When a frontrunner's lead expands against all but one rival, the market consolidates probability from the many into the few.

Whether 52% is justified depends on how you weight Alvarez's closing speed. If the Triple Crown narrative channels Houston's entire organizational effort into maximizing Alvarez's counting stats, 52% may be too high for Stewart. If a 19-RBI deficit is simply too large to overcome in 28 games, 52% may actually be too low. The current price reflects genuine uncertainty, not complacency.

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The Case Against Sal Stewart: Why Yordan Alvarez Could Still Steal the RBI Crown

The strongest argument against Stewart winning the RBI title is that he is competing against a player whose incentive structure has no modern precedent. Alvarez is not merely trying to win an RBI crown. He is trying to become the fifth player in over a century to lead the majors in average, home runs, and RBIs simultaneously. Every September decision the Astros make, from lineup placement to rest days to pinch-hitting usage, will be filtered through the Triple Crown lens.

Stewart, by contrast, is a rookie on a Cincinnati team playing out the string. The Reds have no comparable institutional reason to engineer at-bats around Stewart's RBI total. If Cincinnati falls out of contention, Stewart may see fewer high-leverage plate appearances, fewer runners on base, and potentially rest days to manage workload for a player the franchise views as a long-term asset.

History also favors the chaser in tight September races. Players aware they are trailing a counting stat tend to play with urgency, while leaders sometimes tighten up or see their production regress toward the mean. Alvarez's .329 average and .640 slugging percentage suggest he is not coasting. He is performing at an elite level, and the Triple Crown narrative ensures maximum public and organizational attention on every at-bat.

The 48% implied probability assigned to the field (with Alvarez as the clear leader of that group) reflects a market that sees this race as genuinely competitive. Anyone buying Stewart at 52% is betting that a 19-RBI cushion and four weeks of baseball are enough to hold off a once-in-a-generation pursuit. That bet is defensible, but it is far from safe.

For real-time price movements and the full competitor list, check the Pro Baseball RBIs Leader odds page.