MLB Player Prop Bets for August 21: Four Picks for Thursday

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Publish Date: 08/21/2025

Fact checked by: Meghan

It’s a relatively busy Thursday across Major League Baseball. There are many interesting games happening, and a slew of interesting players playing in such games. That then leads to plenty of interesting prop bets as well.

This guide covers the four individual player bets we like the most for Thursday’s MLB action. All of them are explained based on reason, statistics, and compiled data.

1. Cody Bellinger to Hit a Home Run vs. Red Sox (+520)

Cody Bellinger is just outside the top 20 in home runs on the season. However, he still has 24 long balls on the year and the ability to go deep at any time. He brings that innate power into an extremely favorable position against the Red Sox on Thursday.

Bellinger faces off against Lucas Giolito. Giolito has a decent ERA (3.63) and a great win-loss record (8-2) but he’s also known for giving up the long ball on the road. He’s allowed 10 of his 15 home runs away from Fenway this season and given up a .430 slugging percentage to lefties as opposed to his .387 slugging percentage to righties.

Bellinger is running hot, having hit two home runs just two nights ago, and he returns to a stadium where he’s hit 16 long balls this year. All of that makes this a solid bet that could lead to a good pay out if Bellinger gets a pitch to hit.

2. Corey Seager Over 0.5 RBIs vs. Royals (+170)

Corey Seager may only have 46 RBIs on the season, but he’s another player who falls into a favorable position. He’s a solid hitter who puts the ball in play, and is set to bat third against a shaky Michael Lorenzen (4.43 ERA).

On top of that, Kauffman stadium has the fourth-highest altitude in all of the MLB. That height almost always leads to better offense, which means there will likely be more players on the bases for Seager to hit home. He could easily get a hold of one and go deep as well.

The weather is also on Seager’s side. Kansas City will have the third-highest temperature in the MLB today. Hot games tend to have more offense, and also a reduction in strikeouts. Such factors, combined with Seager’s hitting ability and place in the lineup, make this a bet we like.

3. MacKenzie Gore Under 17.5 Outs Recorded vs. Mets (+110)

MacKenzie Gore is having an extremely shaky year. He’s had plenty of rough outings as of late, and goes up against a strong Mets lineup that’s looking to right their ship. That’s why we like him to have a short stint at home on Thursday.

Gore has a 4.04 ERA on the season, but that has ballooned to a 6.95 ERA over his last seven starts. In that span he’s also only gone over 17.5 outs twice. He’s lasted six innings in his previous two starts, but we like this bet when looking at the whole picture.

Gore is not someone who stays in games long. The Mets aren’t a great team in terms of average, but they get a lot of RBIs and are no stranger to the long ball. Nationals Park also has the fifth-shallowest left field fence in the MLB. That could help New York get some early runs and send Gore to the showers.

4. Sonny Gray Over 5.5 Strikeouts vs. Rays (-139)

Sonny Gray is not having the best season by his lofty standards. He’s posting a 4.30 ERA, and has a 6.62 ERA over his last seven games. Despite that shaky placement, he’s still extremely good at getting strikeouts.

In his last start, despite giving up six runs, Gray tallied seven k’s. He’s also had seven or more strikeouts in each of his last three starts. He’s punching people out at an enhanced rate that doesn’t look to slow down against a Rays team who's right in the middle of the pack when it comes to hitting.

Gray also has averaged slightly more Ks on the road this season (6.4 vs. 6.1) and is 5-4 against the over on this line. The data is in his favor here, and that’s why we like him to cover this spread.

All lines courtesy of FanDuel and BetMGM.