Stacking is an integral part of daily fantasy baseball. Correlation drives upside, giving your lineups a slate-winning ceiling when your stacks explode.

This piece will do the digging and the dirty work each day to determine which stacks are worth rostering on FanDuel's main slate. While we want upside, we also need to factor in game theory, especially in a sport as random as baseball.

The MLB DFS heat map at numberFire is a quick way to get a feel for the overall slate and which offenses are in a good spot. You can also check out our daily fantasy baseball projections -- which are powered by numberFire -- to identify the slate's best bats.

Let's look at the top stacks for today's main slate.

MLB DFS Stacks

Pittsburgh Pirates

Implied Total: 4.43 | Opposing Pitcher: Josiah Gray

The Pittsburgh Pirates suffered their first loss of the season on Wednesday to the Washington Nationals by the score of 5-3. Despite Pittsburgh disappointing in a positive matchup against Trevor Williams, we're going right back to the Pirates on Thursday on a short slate.

Before the Pirates produced three runs on Wednesday, they had tallied six-plus runs in each of their first five games of the season. On Thursday, the Pirates are set to face Josiah Gray, putting them in a prime spot to bounce back.

During his Opening Day start versus the Cincinnati Reds, Gray surrendered seven earned runs and two homers despite striking out six batters in four innings. Gray also allowed a 21.4% barrel rate and 71.4% hard-hit rate in his season debut, so the Pirates could do plenty of damage.

Oneil Cruz ($3,500) and Bryan Reynolds ($3,700) are the primary options in Pittsburgh's lineup. Jack Suwinski ($2,700) hit his first homer of the season on Wednesday, and he should be batting cleanup again with Gray on the bump.

Suwinski has the shortest odds to hit a home run (+300) in Thursday's clash between the Pirates and Nationals.

With the Pirates likely to be popular, using the bottom-of-the-order guys like Henry Davis ($2,700), Jared Triolo ($2,500), and Michael Taylor ($2,800) is a way to be different. Taylor is currently on a six-game hitting streak and has produced 10-plus FanDuel points in five consecutive contests.

Weather could be an issue for the Pirates-Nationals matchup on Thursday, so keep that in mind before lineups lock.

St. Louis Cardinals

Implied Total: 4.30 | Opposing Pitcher: Ryan Weathers

The Miami Marlins are one of two teams that has yet to record a win in 2024, and we'll continue to pick on their pitchers not named Jesus Luzardo. While the St. Louis Cardinals have gotten off to a slow start with their bats, they own the third-best implied total (4.30) on Thursday's main slate against lefty Ryan Weathers.

Weathers allowed three earned runs and seven hits while striking out five in four innings of action in his first start of the season against the Pirates. Even though the Cardinals have sputtered against left-handed pitching to begin the 2024 campaign, they have a few right-handed bats who can excel versus southpaws.

Across 57.2 innings pitched in 2023, Weathers surrendered a .395 wOBA, 1.71 WHIP, and just a 14.5% strikeout rate against right-handed bats, compared to a .384 wOBA, 1.60 WHIP, and 23.4% strikeout rate against lefties.

Both Paul Goldschmidt ($3,500) and Nolan Arenado ($3,000) are understandably going to be the most popular players from the Cardinals. Despite the sluggish start from Arenado, the veteran third-baseman is on a five-game hitting streak.

Willson Contreras ($2,700) led the Cardinals in ISO (.241), wOBA (.384), and wRC+ (145) when facing left-handed pitching in 2023, and he's hit a homer in two of his last three games.

Nolan Gorman ($3,100) is a left-handed batter, but he logged a solid .219 ISO and .361 wOBA in 86 plate appearances versus lefty pitchers last season. On top of that, Weathers had a 2.51 HR/9 and 23.5% HR/FB rate to lefties compared to a 1.66 HR/9 and 13.1% HR/FB rate to righties a season ago.

Washington Nationals

Implied Total: 4.07 | Opposing Pitcher: Martin Perez

As long as weather cooperates, Thursday's contest between the Pirates and Nationals could feature a decent amount of runs. While the Pirates can wreak havoc with Gray on the mound for the Nationals, Martin Perez is the projected starter for Pittsburgh.

Perez is a pitch-to-contact hurler who doesn't possess much swing-and-miss stuff. The experienced left-handed hurler limited the Marlins to one run and six hits in his first start of the season, but he also gave up a 62.5% hard-hit rate and struck out only two batters in 4.1 innings.

With the Texas Rangers in 2023, Perez was in only the second percentile in whiff rate (17.2%) and fifth percentile in strikeout rate (15.3%). This bodes well for a Nationals team that owns the third-best strikeout rate (18.3%) against left-handed pitching since the start of the 2023 campaign.

At the top of the order, C.J. Abrams ($3,300), Lane Thomas ($3,000), and Joey Meneses ($2,800) are enticing options in Washington's lineup. It has been a quiet start to the season for Thomas, but the outfielder registered the 28th-best ISO (.242), 14th-best wOBA (.401), and 15th-best wRC+ (153) against left-handed pitching last year.

Riley Adams ($2,200) and Trey Lipscomb ($2,000) are other players to keep an eye on despite FanDuel currently not projecting Adams to be in the lineup. Adams owned a .232 ISO, .409 wOBA, and 159 wRC+ in 76 plate appearances versus lefties in 2023.

Watch live MLB games and more with B/R Sports on Max! FanDuel customers can now get 50% off the first 6 months of the Max With Ads plan when you bet $5 on any sport via FanDuel Sportsbook. See the promotions page for more information.

Want to play MLB DFS? Head over to FanDuel’s daily fantasy baseball lobby to see all the offerings for today’s slates.

Sign up for FanDuel Sportsbook and FanDuel Daily Fantasy today!

The above author is a FanDuel employee and is not eligible to compete in public daily fantasy contests or place sports betting wagers on FanDuel. The advice provided by the author does not necessarily represent the views of FanDuel. Taking the author's advice will not guarantee a successful outcome. You should use your own judgment when participating in daily fantasy contests or placing sports wagers.