MLB Betting Guide for Monday 8/21/23: Can the Cardinals Support Their Rookie?

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From moneylines to run totals to first-five-inning wagers, we have plenty of ways to bet the long, arduous MLB schedule daily. Outlooks can be vastly different due to starting pitchers, and a wealth of advanced stats can let us know if an individual pitcher, a bullpen, or a team is due for positive -- or negative -- regression.

Using numberFire's projections as a guide, which MLB odds from FanDuel Sportsbook are most appealing today?

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St. Louis Cardinals at Pittsburgh Pirates

Cardinals ML (-126)

Though putting quite a bit of trust into a debuting pitcher to lay this juice, the St. Louis Cardinals' general apparatus today should carry them to a road win.

Drew Rom was acquired when St. Louis shipped Jack Flaherty to the Baltimore Orioles, and he'll essentially take Flaherty's spot in the rotation less than a month later. Rom had a forgettable 4.67 xFIP in Triple-A with the O's, but the Cardinals' well-run pitching development program has helped the lefty turn in a 2.75 xFIP and gigantic 43.9% strikeout rate with Triple-A Memphis.

It doesn't get much easier than the Pittsburgh Pirates as a first MLB assignment when you're a southpaw. Pittsburgh has a 67 wRC+ against left-handers in the past 30 days, which is the fourth-worst in baseball.

The Buccos will mostly turn to a bullpen game in this one. Thomas Hatch will get the start, and Hatch's 4.01 skill-interactive ERA (SIERA) isn't bad, but he also hasn't exceeded 47 pitches in an appearance this year. He'll turn things over to a bullpen with the 10th-highest xFIP (4.34) in MLB this season.

Hatch and the right-hand-heavy Pirates 'pen will have to face a St. Louis squad with a sizzling .770 OPS against righties in the past 30 days. The Cardinals appear to have an advantage wherever Monday's contest heads.

Seattle Mariners at Chicago White Sox

Over 4.5 Runs in F5 Innings (-104)

A shaky version of Luis Castillo is the genesis for this wager.

Castillo's up-and-down 2023 has continued into August where he has a forgettable 4.36 xFIP, but there is significant cause for concern behind it. The righty's 21.0% strikeout rate this month is considerably down from a 27.3% rate this season. All season, Castillo has struggled at times due to a massive 43.0% hard-hit rate allowed, but he's now lost some of the plate discipline control that helped him survive it.

The question is if the Chicago White Sox can take advantage, and I think they can. Their .692 OPS against righties this month is at least an improvement from the league-worst .640 mark from July, so they could be a touch undervalued, having clobbered 10 runs off righties yesterday at Coors Field.

Of course, there's also a chance the Seattle Mariners cover this themselves the way they've been swinging. Led by Julio Rodriguez's hot streak, they've got a scorching 128 wRC+ against righties in the past 30 days entering this date with Touki Toussaint. Toussaint's 23.1% strikeout rate could give the M's a bit of trouble, but a 5.32 SIERA, 16.7% walk rate, and 41.5% hard-hit rate allowed otherwise say he's got the potential to get beat up any time he takes the bump.

Siding with an over, we'll take five and dive in this one because Seattle's bullpen (3.73 xFIP in the past 30 days) has been exceptional all season, and we'd hate to fall a run or two short if they shut things down.

Cincinnati Reds at Los Angeles Angels

Under 4.5 Runs in F5 Innings (-102)

**Editor's Note: This game has been postponed after publishing of this article.**

These two offenses have been dreadful against right-handed pitching lately, so we'll get some value created by a hitter-friendly ballpark in L.A. when backing that trend to continue.

The Los Angeles Angels have an 85 wRC+ against righties in the past 30 days (tied-fourth-worst in MLB), and the Cincinnati Reds haven't been much better (92). These individual offenses have stars, but they're collectively not performing very well, and the two righties on the bump tonight have solid cases to contain them.

Most would point toward Lucas Giolito as the stronger option here, and I'd agree. Giolito's 4.20 SIERA comes with a 24.8% strikeout rate, and he's kept free passes in check (8.4% walk rate), too. Giolito's 45.4% flyball rate is certainly a concern, but the Reds have just a 37.7% flyball rate as a team (18th in MLB) during the past month of play.

However, I wouldn't sleep on Graham Ashcraft on the other side despite a 4.96 SIERA. Ashcraft's peripherals may never be great with a developing sinkerballer profile. He's still ceding just a 29.1% flyball rate, and his 38.9% hard-hit rate allowed is nearly right on the league average. His 4.07 xFIP in August also represents his best month of the season so far, so he's playing his best ball now.

We took a first-five-inning bet in Chicago because the bullpens were solid; we'll do it here for the opposite reason. Both Los Angeles and Cincinnati have bottom-12 reliever xFIPs over the last 30 days.

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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.