MLB Best Bets Today May 21
Seven games are on the betting board today, beginning with Guardians vs. Tigers at 1:10 p.m. ET and finishing with Rockies vs. Diamondbacks at 9:40 p.m. ET. There are only two true getaway day games today, so the other five games have a little bit of runway from a lead time standpoint.
There is also no interleague action today, but we’ll have a good chunk of it for the holiday weekend. But before we get to Friday’s card, we have to work our way through Thursday’s. Only one play for me today, as I considered the Rockies, as that’s a big price on Eduardo Rodriguez and his cornucopia of regression signs, but the Rockies bullpen is absolutely gassed and it’s a bullpen day for them.
I’ll be posting my daily best bets Monday-Saturday with a Sunday Night Baseball preview on Sunday, as all the day games make it tough to get something out with lead time out here in Las Vegas. All lines are from DraftKings and are current at the time of publish. Please take the initiative to SHOP AROUND for the best odds. It matters. A lot.
One new offering this baseball season is our Opta AI Player Prop Projections. They are for VSiN Pro Subscribers only, so you can check out our current offers here. Zachary Cohen will be using those projections and his own handicapping to write up MLB player props.
Greg Peterson will have his best bets posted the night before and you can also check out his daily lines to see what looks to be off-market. Steve Makinen has also released his updated Bullpen Betting Systems and DraftKings Splits Systems, plus he’ll have a daily analytics report.
Feel free to use my opinions and thoughts, as well as our suite of MLB Betting Tools, including the DraftKings and Circa Betting Splits, Steve Makinen’s Daily Ratings, Greg Peterson’s Daily Lines, the 1st 5 Innings Analyzer, and Umpire Stats. Check out our new MLB tools powered by Ballpark Pal: Strikeout Projections, Park Factors, and YRFI Report.
Here are the MLB best bets today for May 21:
Atlanta Braves (-143, 7.5) at Miami Marlins
6:40 p.m. ET
Spencer Strider and Sandy Alcantara are the listed starters here, as every start for these two guys is a good thing with their recent health histories. And, it turns out that both are throwing the ball pretty well right now.
FanGraphs posted a big write-up on Alcantara by Michael Baumann that basically noted how Alcantara’s pitch mix is working for him and how encouraging this season has been. It’s true. While Alcantara only has 45 K in 63.2 innings of work, he’s got a .284 BABIP against with a 49.% GB% and a 6.0% HR/FB%. He isn’t generating strikeouts, but he’s inducing a ton of weak contact with a 35.8% Hard Hit% and a 5.0% Barrel%.
Even with a six-walk outburst against the Brewers earlier this season, Alcantara has a 2.95 ERA with a .189/.270/.294 slash and a .259 wOBA against over 39.2 innings at home. That pretty much falls in line with what his home/road splits have looked like. Even last season when he had an ERA north of 5.00, he had a 4.40 ERA in 108.1 innings at home with a .224/.275/.366 slash against and a .280 wOBA compared to a 6.92 ERA in 66.1 innings away from home and was +58, +87, +97 and +77 in those other metrics.
So, I’d expect him to pitch well today at home. The Braves recently lost Drake Baldwin to injury and just welcomed Ronald Acuna Jr. back, so this offense isn’t running on all cylinders right now like it was earlier this season. Alcantara is a workhorse and will likely pitch deep into this game, but the Marlins only used one reliever and a position player yesterday after Janson Junk’s start, so the bullpen is very fresh.
I was very surprised when Strider made his 2026 debut at Coors Field. I probably would have considered moving him to an easier assignment, given the difficulties of pitching at Coors, especially for a guy coming off of injury. I wouldn’t want any bad habits to develop as a result of that start. And, as expected, Strider struggled, allowing three runs on four hits in just 3.1 innings with five walks against six strikeouts. Since then, though, in starts against the Dodgers and Red Sox, he’s allowed one run on four hits in 11.1 innings of work. While he has walked five, he’s struck out 12. More importantly, he’s only allowed six hard-hit balls and one Barrel, as he has a 33.3% Hard Hit% and 6.7% Barrel% through three starts.
He’s got a 13.7% SwStr% and a lot of metrics that fall in line with what we’d expect from a guy like Strider. I’m sure he’s still working through some things, but the Marlins are 23rd in wOBA over the last 14 days against RHP at .274, even though they only have a 16.6% K%. Not a lot of contact authority in there.
The Braves pen is well-rested off of yesterday’s blowout win, so when Strider’s rope runs out, the better arms are available for manager Walt Weiss.
Pick: Under 7.5 (-111)
