Stewart Leads MLB With 102 RBIs But Market Has Him at 40%

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Sal Stewart Leads MLB With 102 RBIs, So Why Are His Prediction Market Chances Dropping Fast?

Sal Stewart of the Cincinnati Reds leads Major League Baseball with 102 RBIs as of August 28, 2026, but his probability of finishing as the Pro Baseball RBIs Leader has fallen from 49% to 40% in three days, one of the sharpest drops for any statistical-leader market this season. He is a 21-year-old rookie who just broke the Reds' all-time rookie RBI record previously held by Jim Greengrass since 1953. By every traditional measure, he should be the clear favorite to finish the year on top.

Kalshi prices him at 40%; Polymarket sits at 41%. The remaining 60% of probability is distributed across the rest of the field. Five weeks and roughly 30 to 35 games remain before the September 28 resolution date.

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The core puzzle: Stewart has not been placed on the injured list, has not entered a documented slump, and hit his 29th home run on August 28 while collecting RBIs 101 and 102 in a game against the Cubs. The market is not reacting to something Stewart did wrong. It is reacting to something one or more challengers are doing right.

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Who Is Chasing Sal Stewart in the 2026 MLB RBI Race?

The identity of the specific threat matters more than Stewart's own production at this point, because the market is repricing the field, not downgrading the leader. A 102-RBI pace through late August projects to roughly 118 to 122 RBIs over a full season, depending on plate-appearance totals. Any hitter sitting in the 94-to-98 range who is on a hot streak entering September can realistically close that gap.

For context, the average MLB hitter with regular playing time produces between 18 and 25 RBIs in September. A hitter locked into a hot lineup slot, batting cleanup for a contending team with high on-base runners ahead of him, can push 30 or more in the final month. That means a challenger trailing by 6 to 8 RBIs entering September needs only a moderately above-average final month to pull even, provided Stewart cools off even slightly.

The math works like this: Stewart's season-long pace is roughly 0.72 RBIs per game. If a challenger is running at 0.90 or higher over a sustained stretch, the gap closes by roughly 5 to 6 RBIs per 30 games. That is enough to erase a seemingly comfortable lead, which is precisely the scenario the prediction market appears to be pricing.

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The Case Against Stewart Winning the RBI Title: What the Bears Know

The strongest version of the bear case starts with history. Late-August RBI leaders do not hold on as often as casual fans assume. From 2015 through 2024, the player leading in RBIs on September 1 finished the season on top roughly 65% of the time, meaning about one in three leaders was overtaken. Stewart's current market price of 40% implies he is less likely to hold on than the historical base rate would suggest, which means bettors are factoring in something specific beyond normal reversion.

One possible factor: Stewart's rookie status. [Analysts have noted that he faces stiff competition from players like Nolan McLean and JJ Wetherholt for Rookie of the Year, indicating that multiple young players are performing at elite levels this season. Veteran challengers with deeper September track records may benefit from lineup protection and postseason-race urgency that a rebuilding or fringe-contending Reds roster cannot match.

Schedule also matters. If Cincinnati's September slate features a disproportionate number of road games against strong pitching staffs, Stewart's RBI opportunities shrink. Conversely, a challenger playing home games against weaker rotations gets more favorable plate appearances. A 40% probability for a player holding a clear lead implies the market sees structural disadvantages that offset the raw counting-stat cushion.

The 60% allocated to the field is not a vote of no confidence in Stewart. It is an acknowledgment that five weeks is a long time, that multiple credible threats exist, and that RBI totals are partly a function of context (lineup position, runners on base, game situations) rather than pure individual skill.

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Sal Stewart's Chances Over Time: Reading the Three-Day Price Drop

The three-day chart reveals a steady, not sudden, decline. Stewart's probability did not collapse in a single session, which would indicate a specific injury or trade rumor. Instead, the gradual slide from 49% to 40% suggests accumulating information: daily box scores from challengers, lineup changes, or a broader reassessment of the September outlook across multiple competing hitters.

Worth noting: Stewart's period low in this market sits at 30%, meaning he has traded as low as 30% and recovered to 40%. That 10-point swing from the floor shows that bettors have been willing to buy Stewart at lower prices before, establishing a rough support level. If his probability approaches 30% again without a clear injury, it may represent a buying opportunity for those who believe the RBI lead provides a structural edge.

The gap between Kalshi (40%) and Polymarket (41%) is narrow enough to confirm cross-platform consensus rather than a single-venue anomaly. Both markets are telling the same story: Stewart is still the single most likely winner, but barely.

Stewart's 102 RBIs are real. His broken rookie record, first documented by Wire Report, is permanent. But the market is telling you that a lead and a title are two different things, and five weeks is more than enough time for someone to close the gap.