Best MLB bets today: Mets vs. Mariners prediction, picks, props for August 15

Teams with MLB postseason aspirations begin a weekend series on Friday night when the New York Mets host the Seattle Mariners. The Mets have lost 13 of their last 15 games and are five games behind the Philadelphia Phillies in the NL East, while the Mariners have won eight of their last 10 and trail the Houston Astros by just 1.5 games. First pitch is scheduled for 7:10 p.m. ET, and the game will be shown nationally on MLB Network.

If you're looking to get into MLB betting at the top sportsbooks, check out the SportsLine Projection Model for the latest Mets vs. Mariners odds, predictions and player props. The model entered Week 21 of the 2025 MLB season at a profitable 31-23 on top-rated MLB money line picks.

Sean Manaea (1-1. 4.33 ERA) gets the ball for New York. The veteran southpaw has only pitched 27 innings this season after starting the year on the IL, but he's been more effective than his ERA would suggest since returning to action. FanDuel Sportsbook has Manaea set at 5.5 strikeouts, with the Over priced -106 and the Under at -118. The model has a slight lean to the Under.

Seattle counters with Luis Castillo (8-6, 3.19). The right-hander has been a key part of the Mariner rotation, almost quietly so given the breakout excellence of Bryan Woo. Castillo is set at 4.5 strikeouts at FanDuel, with the Over priced -130 and the Under at -102. The model rates the Over 4 stars out of 5.

Breakout Seattle star Cal Raleigh has shortest odds to hit a home run at FanDuel at +230. He's followed by Eugenio Suarez (+300), Juan Soto (+300), Pete Alonso (+330), Randy Arozarena (+330) and Julio Rodriguez (+340). 

The Mets are -121 favorites to win (wager $121 to win $100) in the latest SportsLine consensus odds, while the Mariners are +102 (wager $100 to win $102) underdogs. The total sits at 8.5, with the Over favored at -122.

Here are the SportsLine model's projections for Mets vs. Mariners on Friday.

SEATTLE MARINERS at NEW YORK METS | 8/15 | 7:10 p.m. ET

Money line
Pick: Mariners +102
Seattle wins in 54% of simulations, bringing value at these odds

Run line
Pick: Mariners +1.5 (-201)
Seattle covers in 74% of simulations, bringing value at these odds

Over/Under
Pick: Over 8.5 (-122)
The Over hits in 54.6% of simulations, bringing value at these odds

Projected score: Mariners 4.9, Mets 4.3