MLB Betting Guide for Friday 4/21/23: 3 Unders to Target on a Slate With Weather Concerns

Betting on baseball can be a grind that reaps an enormous reward.

Day-to-day outlooks can be vastly different by starting pitchers, and a wealth of advanced stats can let us know an individual pitcher or team is due to positive -- or negative -- regression.

Which MLB lines from FanDuel Sportsbook are most appealing today?

Note: Lines are subject to change throughout the day after this article is published. All stats come from FanGraphs unless noted otherwise. Please check here to make sure you're seeing the most updated information.

Oakland Athletics at Texas Rangers

Under 8.0 (-102)

When the Athletics are the better offense in their split for the day, the under should be on our radar.

With an 85 wRC+, Oakland has a higher output against righties than Texas does against lefties (74 wRC+). There's a pretty sizable gap in the quality of hurlers representing those platoons, but it's still an excellent starting point.

The A's have a date with Jon Gray, who has shown flashes of why he was the third pick from the 2013 MLB Draft. Gray's 4.42 xFIP is in a pretty solid spot considering his opponent tonight, and he's done an exceptional job limiting hard contact this season with a 32.1% hard-hit rate allowed.

JP Sears isn't quite on that same level, but his 4.73 skill-interactive ERA (SIERA) is far from the worst in his rotation, and he's also got a modest hard-hit rate allowed (35.1%).

These poor offenses should help the average pitchers out in this one.

San Diego Padres at Arizona Diamondbacks

Diamondbacks ML (-104)
Under 9.5 (-114)

Maybe it's the buzz around Fernando Tatis Jr. returning, but this total makes no sense, and the Diamondbacks should be favored.

San Diego has just a 93 wRC+ against right-handed pitching, and it's Zac Gallen Day for the Snakes. Gallen's start to 2023 has been masterful, accruing a tiny 3.20 SIERA and a whopping 29.5% strikeout rate. This is a below-average offense taking on an ace.

The Friars wouldn't call Seth Lugo their ace, but he's pitched like one to start the year, too. Lugo's 3.55 SIERA is in close proximity to Gallen's, and he's also worked into the seventh inning twice for anyone concerned about the former reliever's pitch limit.

The D-Backs (91) have an even lower wRC+ against righties than the Padres. This under was an immediate priority at such a lofty number. With Gallen's long track record of success, he's more reliable at home on the mound, so Arizona's moneyline is worth a gander for the same reason.

New York Mets at San Francisco Giants

Under 8.5 (-102)

This is yet another pitching matchup where the name value sounds concerning, but these hurlers are quietly in a solid spot.

Anthony DeSclafani's bounce-back year for the Giants is one of the feel-good stories in MLB thus far. The former Reds ace has a minuscule 1.42 ERA that's well supported by a 2.86 SIERA, and he's rediscovered some swing-and-miss ability (23.5% strikeout rate).

He'll face a Mets lineup with that's not easy for a righty, but New York's .730 OPS in that split thus far is down from their mark a year ago (.756). New York will counter with Joey Lucchesi, and the former Padres standout has worked his way back to the bigs for the first time since 2021.

Lucchesi has held a 2.30 ERA in AAA this year with his usual worm-killing 53.8% ground-ball rate. MLB tests don't get much easier for a lefty than the Giants, whose .593 OPS is the second-worst in MLB to this point.

Combined with the cooler marine air in San Fran, we can take a swipe at these two former aces channeling a bit of that form once again.