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.

Our MLB DFS heat map 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 to identify the slate's best bats.

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

Los Angeles Dodgers

At this time of year, implied team totals tend to be on the lower side, and Friday is no exception, as every team is implied for fewer than five runs. Four teams check in above four, though, and the Los Angeles Dodgers are one of them.

They'll face Merrill Kelly, who's hardly a bad pitcher but has stark splits that should interest us today. While Kelly posted solid overall numbers last year, he was much less effective against left-handed batters, producing a 4.60 xFIP, 19.1% strikeout rate, and 10.2% walk rate. He also allowed a 40.5% fly-ball rate in the split, leading to those lefties churning out 1.23 home runs per nine innings.

This makes Freddie Freeman ($3,900) and Max Muncy ($3,200) easy to like. While Muncy had a bit of a down year in 2022, keep in mind that he was coming off a serious elbow injury from the previous season and still produced a .188 ISO with a 91st-percentile barrel rate.

We can also roster some lefties on the cheap through David Peralta ($2,300) and James Outman ($2,200). Although Peralta isn't known for his power, he put up career-highs in fly-ball rate (41.1%) and barrel rate (8.5%) last season. Outman made just 16 big league plate appearances in 2022, so he's more of a wild card, but he demonstrated promising power in Triple-A and all public projection systems see him hitting double-digit home runs this year.

Kelly is admittedly tougher on righties, so that reduces their appeal somewhat. But that shouldn't stop us from rostering studs like Mookie Betts ($3,900) and Will Smith ($3,400), who are pretty much always in play, and this isn't a bad salary to get in on J.D. Martinez ($2,900), too.

San Diego Padres

The San Diego Padres are another team with an implied total above four runs, and they'll benefit from a matchup against southpaw Kyle Freeland.

Freeland was thoroughly mediocre in 2022, logging a 4.51 SIERA and 17.1% strikeout rate over 31 starts, and that strikeout rate dipped to just 16.6% versus righties. But perhaps what is even more damning was the fact that he wasn't even all that great against lefties and was lit up for 1.77 home runs per nine innings in the split.

All of this makes the Padres especially easy to stack on both sides of the plate. Manny Machado ($3,900) and Juan Soto ($4,000) are no-brainers, and Xander Bogaerts ($3,200) is an appealing value if he's batting leadoff as projected.

Best of all, everyone else in the lineup should come in at $3,000 or below. Nelson Cruz ($2,500) might not be the player he used to be, but he was still an above-average hitter with the platoon advantage last year (106 wRC+) and could bat as high as fourth. Jake Cronenworth ($3,000) can hold his own in lefty-lefty matchups and had a respectable .155 ISO in the split last year.

Seattle Mariners

The Seattle Mariners have a matchup against an unknown commodity in right-hander Hunter Gaddis, but it's one we might want to pounce on anyway.

Gaddis only made two starts in 2022, but boy, they sure didn't go well. The 24-year-old produced an ugly 6.54 SIERA and 12.5% strikeout rate over 7 1/3 innings and coughed up a whopping seven home runs.

Although Gaddis did post a 30.9% strikeout rate in nine Triple-A starts, those early returns aren't exactly a ringing endorsement. The dingers might not be entirely a fluke, either, as he's been an extreme fly-ball pitcher throughout his minor league career.

Julio Rodriguez ($4,000) needs no introduction, and if you can't get up to him, there's still plenty of power to be found between Teoscar Hernandez ($3,600), Cal Raleigh ($2,600), and Eugenio Suarez ($3,000), all of whom cracked a .220 ISO last year. Kolten Wong ($2,700) and Ty France ($2,900) are nice values as the expected number two and three hitters, and Jarred Kelenic ($2,600) has some pop lower in the order.

While it's an incredibly minuscule sample size, Gaddis didn't record a single strikeout against any of the nine left-handed batters he faced last year, so you could consider bumping up Seattle's lefties in case that's a sign of things to come.