MLB Best Bets for September 13: Three MLB Unders for Wednesday’s Slate

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Zack Gelof #20 of the Oakland Athletics scores during the third inning ahead of Martin Maldonado #15 of the Houston Astros. Carmen Mandato/Getty Images/AFP

MLB Pick: Athletics-Astros Under 9 (-113) at Heritage Sports (visit our Heritage Sports Review)

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We have a full Wednesday MLB card with all 30 teams in action. As of this hour, the Angels have yet to name their starter, while the Pirates, Brewers and Royals are all using openers. 

We are here with our three best bets as usual and remember that these are value bets mostly based on our proprietary model, so when we make underdog plays, it means we project long-term profit at the odds posted, even with a sub-.500 record.

Despite the full schedule, we do not see much underdog value for this day, but we do see three Under plays that we feel have value, and we are making those our best bets at the top sportsbooks.


Atlanta Braves vs. Philadelphia Phillies

Wednesday, September 13, 2023 – 06:40 PM EDT at Citizens Bank Park


Spencer Strider of the Braves has been one of the best pitchers in baseball and he keys this Under play visiting Cristopher Sanchez and the Phillies.

xFIP and K-Rate Leader

Strider may have a higher ERA than expected at 3.83, but he leads the Major Leagues in xFIP at 2.91, and his sensational strikeout rate of 13.89 K/9 also leads the majors by a wide margin, more than two strikeouts per 9 higher than second place Blake Snell. And that is while limiting his walks to a manageable 2.89 BB/9, the lowest mark of his professional career including the minors.

Strider averages an impressive 97.4 MPH, but he has shown the ability to reach back for more when he needs to while occasionally hitting triple-digits on the radar gun. Granted, Spencer comes off one of his worst starts of the year, allowing six runs in just 2.2 innings, but it was revealed he was dealing with an illness that day and the assumption is he would not be pitching tonight if that was still an issue.

Holding His Own

Now Sanchez may not be at Strider’s level in terms of ability while sporting a 2-3 record but, believe it or not, he enters this contest with the better ERA at 3.26, a figure that is legitimized but his equal 3.26 xFIP.

Cristopher has a very good K/BB ratio of 8.21/1.46 per 9 as well as an excellent groundball rate of 58.6%, keyed by his heavy 93.6 MPH sinker. He has also been ultra-consistent, allowing more than three earned runs just once in his 15 starts.

So with Strider already at an elite level and Sanchez showing great potential that may propel him to reach that level in a couple of years, go Under at +105 betting odds in Philadelphia.

Predicted Score: Braves 4 – Phillies 3

MLB Pick: Under 8.5 (+105) at Bookmaker (visit our Bookmaker Review)

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Texas Rangers vs. Toronto Blue Jays

Wednesday, September 13, 2023 – 07:07 PM EDT at Rogers Centre


We see the potential for a sneaky-good pitching duel Wednesday and are backing the Under when Yusei Kikuchi and the Blue Jays host fellow southpaw Jordan Montgomery and the Rangers in Toronto.

Less Walks = Best Season

The 32-year-old veteran Kikuchi has always struggled with wildness since entering the Major Leagues in 2019 after pitching in Japan, but he has had amazing improvement in that area this year, cutting his walks in half since last year from an ugly 5.19 BB/9 all the way down to 2.60 BB/9 and is now having his best Major League season at his advanced age.

Yusei is 9-5 while posting a career-best 3.57 ERA that is accompanied by a good enough 3.80 xFIP, and he is still striking out more than one batter per inning with 9.69 K/9. Perhaps most telling is Kikuchi’s average velocity this season of 95.2 MPH is higher than his career average of 94.4 MPH, so he is certainly not showing signs of aging.

Fine Overall

Now, we have had a love/hate relationship with Montgomery all season due to his erraticism, but the bottom line is he still sports a solid 3.62 ERA through 28 starts covering 161.2 innings for the Cardinals and Rangers combined, and he won his only start vs. the Blue Jays while limiting a potent lineup to three runs and six hits.

One possible red flag is the 4.04 xFIP, but that figure has been at 3.76 since August 1st, and while Jordan can be qualified as “crafty” with his heavy use of curveballs and change-ups, his average fastball velocity this season of 93.5 MPH is actually a career-high.

So with Kikuchi having his best season and Montgomery lowering his xFIP lately, go Under north of the border.

Predicted Score: Blue Jays 4 – Rangers 3       

MLB Pick: Under 8.5 (-114) at BetOnline (visit our BetOnline Review)

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Oakland Athletics vs. Houston Astros

Wednesday, September 13, 2023 – 07:10 PM EDT at Minute Maid Park


Look for a relatively low-scoring game in relation to the posted total today when Hunter Brown and the Astros host Paul Blackburn and the Athletics at Minute Maid Park.

Better Than the ERA

The rookie Brown may be 10-11 with a 4.78 ERA, but he comes with upside, as evidenced by the substantially better 3.44 xFIP. He combines a very good strikeout rate of 10.32 K/9 with a nice groundball rate of 52.5%, a combination that is usually a recipe for success.

That success has eluded Brown, though, since he has not had much luck, with a .343 BABIP allowed and a 69.4% strand rate. He does benefit here from facing an Oakland lineup that has been 10% below average vs. right-handers with a wRC+ of 90, and a lineup that Hunter had handled well in three starts this season, allowing two runs or less on every occasion.

Best Starter?

Blackburn may be the closest thing the Athletics have to being an ace, as he has managed to go 4-4 with a commendable 3.88 ERA and 4.18 xFIP since making a belated season debut on May 29th.

Paul also has a career-high strikeout rate of 9.23 K/9 that smashes his previous high of 7.71, and that uptick seems real with his 10.1% swinging strike rate at its highest point since 2019, Furthermore, the ERA would be even better if not for an unlucky .359 BABIP allowed.

Finally, Blackburn allowed just one run on five hits in his only start vs. Houston this year, which when combined with Brown’s success vs. Oakland and his general upside, has us betting the Under on Wednesday.

Predicted Score: Astros 5 – Athletics 2

MLB Pick: Under 9 (-113) at Heritage Sports

*The line and/or odds on picks in this article might have moved since the content was commissioned. For updated line movements, visit BMR’s free betting odds product.