Chalk of the Day, August 9: Matt Olson to homer at +263

The most-bet home run prop on the Sunday board, checked against 5,000 play-by-play simulations of Atlanta at the Yankees. The +263 price implies 27.5%. The simulations say 20.5%. Negative EV at about -26%; it becomes a play at +388 or longer.

Written by Jesse, NegativeEV. Last updated 9 August 2026.

Watch: https://youtube.com/watch?v=xQgZBnh1TmY

• Sample: 5,000 pitch-by-pitch simulations of one game
• Window: 9 August 2026 slate
• Priced at: +263, the day's books ranged +220 to +273, read the morning of the game
• Measured: 2026-08-09

Narration on the episode is synthetic, voiced from the written read; the analysis is the simulator's.

The bet

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Across 5,000 simulations Olson's average is 0.23 home runs and the median is zero. He homers exactly once in 18 of 100 simulations and twice or more in about 2 of 100. At 5,000 simulations the standard error on the number is 0.57 points, so the gap to the price is roughly fourteen times the error bar — a re-run would not move our number that far. That is a statement about our own noise, not a proof the book is wrong.

What works against him

The matchup. Cam Schlittler suppresses home runs (top quarter of 227 pitchers by HR rate allowed) and misses bats (top 10% strikeout rate). Neutralize his career profile alone and Olson's number rises from 20.5% to 22.7%.

What works for him — and it is a lot

• His own bat. Olson is tied for the NL lead with 33 home runs (two behind Yordan Alvarez's 35 overall). His season form arm is worth 3.2 points and his career profile another 2.5 — top-10% exit velocity, a .075 HR rate this season against .069 career.
• The weather. 90 degrees, wind 8 mph out to right field at Yankee Stadium, the second-friendliest home run park in baseball (park factor 1.35). The weather arm alone is worth 3.1 points.
• The road. Batting third for the away side, he is guaranteed all nine innings: 1.0 point. He averages 4.66 trips to the plate; his homer rate is 15% on four trips, 23% on five, 31% on six. On six trips the play would actually flip positive at this price.

Why it still grades negative

That is the whole lesson of the segment: nearly everything measurable pushes this number up, and the price is still too expensive. A bet is not a question about whether the thing might happen — Olson very well might homer today. It is a question about the number next to his name, and +263 pays as if his chance were 27.5% when the simulated games put it at 20.5%. Plays like this are how a board that looks exciting grades out negative over a season.

Method

The game is simulated pitch by pitch 5,000 times from the projected lineups, and the prop is graded on how often it lands. 37 factors were neutralized one at a time, each arm a separate 4,000-simulation re-run, so one-at-a-time swings do not sum to the projection. Prices as posted the morning of the game; the check is against the quoted price, rake included.

Written up for readers: https://negativeev.com/about/home-run-props All findings: https://negativeev.com/research