3 MLB Batter Props to Back on September 5: Alonso, Semien, and Naylor Hit Value Plays

Friday’s slate is stacked with batter prop value if you know where to look, and three matchups stand out above the rest: a favorable lefty look for Pete Alonso, a red-hot Marcus Semien riding a monster September surge, and a contact-machine in Josh Naylor getting a soft matchup against a fringe Athletics arm. These aren’t gut-feel picks — they’re built on projection models, recent form, and real market inefficiencies in the current lines.

Each of these three bets clears real analytical thresholds: model cover rates north of 55%, and in one case, expected value pushing past 50%. Here’s the breakdown on all three, position by position.

Pete Alonso Feasts on Lefties in His First Season with Baltimore

Pete Alonso draws Ranger Suarez, and the model likes this spot a lot. Alonso is projected for 1.0 hits on the day, translating to a 71% cover rate on the hits market — that’s the kind of number that should be moving the -201 price on the hits over, not sitting where it is. The total bases side offers the better number: Alonso at +127 on the over 1.5 total bases line represents real plus-money value on a player projected to clear it with room to spare.

Alonso has been one of the more consistent total-bases performers in the league all year, and lefty pitching hasn’t been a significant equalizer for him this season the way it can be for other right-handed sluggers. Suarez’s stuff plays fine against average bats, but Alonso isn’t an average bat — he’s a middle-of-the-order power threat who turns mistakes into extra-base hits at an elite clip. When the model’s hit probability and the total-bases price both point the same direction, that’s a signal worth acting on.

Bettors chasing plus-money value on a projected performance this strong should also check the Expected Value (EV) Calculator to see exactly how much edge a price like +127 carries relative to Alonso’s true hit probability.

Marcus Semien’s September Surge Makes This an Easy Total Bases Play

Marcus Semien facing Giants lefty Matt Wilkinson is the sharpest number on the board today. The model has Semien covering the Over 1.5 Total Bases line at a 57% clip, and more importantly, the expected value on the +173 price checks in at an eye-opening 54.7% EV — one of the largest edges in the entire prop pool for Friday’s card.

Context matters here. Semien has historically turned it on in September, and this year is no exception — he’s been running well above his season norms over his last stretch of games, hitting extra-base pitches with more authority than his overall .216 season average would suggest. Against a matchup like Wilkinson, a lefty the model doesn’t view as a significant equalizer, Semien’s pop plays up. When a total-bases price offers plus-170 or better odds on a player trending this hot, that’s typically a market lagging behind recent form — exactly the inefficiency sharp bettors look to exploit before the price corrects.

Josh Naylor’s Contact Skills Erase the Value in a Short Athletics Line

Josh Naylor against Athletics right-hander K. Morris is the safest of the three plays, and the numbers back that up. The model projects Naylor for 1.2 hits in this matchup with a 74% cover rate on the Over 0.5 Hits line — the highest hit probability among all three picks today. The market has priced this appropriately tight at -226, but that number still undersells just how difficult Naylor is to keep off the bases against a fringe arm like Morris.

Naylor is a career .268 hitter who has feasted on the Athletics historically, and Morris simply doesn’t miss enough bats to change that equation. Even accounting for the short odds, a 74% model-projected cover rate against a shaky starter is the type of “safe anchor” leg that sharp bettors like to build around — the reliability here offsets the lower payout, especially if paired with either of the two plus-money bats above in a same-game or cross-game parlay structure.

Today’s Edge

All three of these plays clear real thresholds — model-projected hit rates in the high 50s to mid 70s, and total bases value that includes one of the sharpest EV numbers on the board. Here’s the full rundown:

• Pete Alonso OVER 1.5 Total Bases (+127) vs. BOS LHP Ranger Suarez
• Marcus Semien OVER 1.5 Total Bases (+173) vs. SF LHP Matt Wilkinson
• Josh Naylor OVER 0.5 Hits (-226) vs. ATH RHP K. Morris

Whether you’re stacking these into a parlay or playing them straight, the combination of favorable matchups and model-backed cover rates makes this trio one of the sharper batter-prop cards of the week.