MLB Second Half Preview | 7 Overvalued Pitchers to Bet Against, Including Zac Gallen, Mitch Keller

MLB Second Half Preview | 7 Overvalued Pitchers to Bet Against, Including Zac Gallen, Mitch Keller article feature image

Chris Coduto/Getty Images. Pictured: Zac Gallen

The second half of the MLB season begins on Friday after the All-Star break reaches its conclusion. At the beginning of the season, I wrote about a handful of pitchers that I was looking to bet against, including Alek Manoah, Cal Quantrill, Shane Bieber, and Sandy Alcantara.

The market catches on to the breakouts and the disappointments pretty quickly, but changes in velocity, stuff and underlying projections can provide value going forward betting on and against certain starters.

Here are seven potentially overvalued pitchers I’m looking to bet against in the remainder of 2023.

For each pitcher, I've also included their record and ROI (for a $100 bettor) if you had bet on them in each start so far in the 2023 season. Data for that is provided by BetLabs.

To see Anthony Dabbundo’s MLB bets throughout the 2023 season, follow him on the Action App.

Zac Gallen, Diamondbacks

First Half Betting Record: 14-6, +$357

Gallen has been one of the most valuable pitchers in all of baseball this season and is one of the Cy Young favorites in the National League. It's clear that Gallen is in the upper-echelon of MLB starters, but the question is whether his current level is sustainable. I'd argue it's not. Gallen's xERA (3.62) is more than a half run higher than his actual number (3.04) and there's nothing in the profile that looks all that different from years past to suggest he's taken the leap into the tier that the market has priced him.

The real skills difference for Gallen has been a drop in his walk rate from improved command. His first pitch strike rate is up just marginally, as is his zone rate. If you buy this command improvement to last, then you can say Gallen is elite. But given his track record and past history of inconsistent command, Gallen's walk rates for the remainder of 2023 should be regressed closer toward his 7.9% career average, not his 4.9% in 2023.

The Diamondbacks and Gallen are likely at the peak of their market value right now and he's likely to be slightly below that going forward. Even his Stuff+ rating is not among the top 10 MLB starters but closer to a No. 2 starter.

Mitch Keller, Pirates

First Half Betting Record: 11-8, +$367

Keller featured in the 'potentially undervalued' preseason column and that has certainly been the case through the first half of 2023. Like Gallen, the breakout is banked on extremely improved command numbers and we have to question whether Keller can maintain that going forward. Keller has a seven percent walk rate in 2023, compared to a 9.1% career number.

His strikeout rates have taken a huge leap from a solid 20% in 2022 to an excellent 26.7% in 2023. In order for that to be sustainable, you'd need to see a significant uptick in chase rates or whiff rates against him. Neither is the case. Keller's swinging strike rate is 8.8%, below the league average. His chase rate is below league average too, and less than last season.

There will be more balls in play against Keller going forward and that will hurt him. I'm skeptical of him maintaining his elite ratios, even if he's clearly an established solid starter now.

Bryce Miller, Mariners

First Half Betting Record: 12-7, +$102

Miller dazzled in his first few starts with elite fastball Stuff+ and whiff rates. No one could hit the pitch at first, but as it has lost velocity he's seen a decline in results. Miller averaged 95.5 mph or more with his fastball in his first three outings, and he's failed to top 94.6 in four of his last five outings. The difference between 96 and 94.5 doesn't seem like a lot, but it is when you're so reliant on the heater for success. He's throwing his fastball 68.2% of the time.

The Stuff+ has dropped off on the fastball and there are some signs that hitters may be able to pick up on the tiny differences in release points when he throws his breaking balls. Miller has a solid 3.97 ERA thus far in his MLB career, but when he returns from this blister injury, it'll be important to monitor his fastball velocity.

He's likely a mid-4s ERA pitcher at the moment and will be likely overvalued by the market.

Luis Severino, Yankees

First Half Betting Record: 4-5, -$102

Severino's rolling chart of strikeouts per nine and xFIP are extremely concerning. His fastball velocity has dropped off and he's lost movement on the pitch. The results for him in the last two months have fallen off a cliff.

It all started in early June with a start against the Dodgers. He dominated the Reds and Padres in his first two outings, but he has a 9.48 ERA in the last seven starts.

It's surprising that the Yankees keep pitching him every five days at this point. One wonders if the rest of the rotation injuries have forced their hand a bit. Severino has lost about 1.5 mph on the heater and he's under a strikeout per inning. Given his usually elite stuff, this is alarming and suggests potential mechanical issue or injury.

I'll keep fading until he proves he's anywhere close to the elite form he's showed in years past. Just watch the radar gun. If he's consistently in the 95s, it's big trouble.

Shane Bieber, Guardians

First Half Betting Record: 7-12, -$640

Bieber is once again overperforming his underlying indicators, but the underlying indicators just keep getting worse by the year. Bieber has fallen very far from his elite numbers in 2020 and 2021 to the point where his strikeout rates are solidly below league average. Stuff+ says he has below average stuff too.

Bieber has a rolling xFIP over 3.60, an xERA of 4.84 and his new cutter is allowing an xSLG of .517 this season. The cutter was supposed to help him overcome the skills and stuff loss on his other pitches by inducing weak contact, but it hasn't been effective for him.

The trade rumors for him — given how well run the Guardians are usually — is a hint that Cleveland knows it's better to sell now than when it may be too late given the skills loss.

Nathan Eovaldi, Rangers

First Half Betting Record: 10-9, -$180

By the fantasy calculators, Eovaldi has been the most valuable starting pitcher in all of MLB. A quick look at his underlying profile from the entire first half and you'd see no real reason to fade him. He has a solid K-BB% and his xERA of 3.39 is among the better MLB starters.

Eovaldi's path to that production offers some concerning alarm bells though.

Eovaldi averaged at least 95.7 mph with his fastball in every start in April and May. The Rangers saw what everyone else did in the numbers and insisted the loss of velocity in June was a matter of mechanics, not fatigue or injury. Eovaldi has hit 95.7 mph with the fastball in one of his last seven starts, and four of the last five have come in below 95.0 mph.

The loss of fastball velocity will show itself in a jump in homers allowed and a drop in strikeouts. We've seen this before with Eovaldi, who really struggled last season before ending up injured.

The market has downgraded him because of the velocity loss, but there's room to fall even further.

Bryce Elder, Braves

First Half Betting Record: 13-5, +$441

Elder is one of the more obvious fade candidates on the entire board. All you have to do is sort xERA and compare it to actual ERA and you'll see that Elder is one of the most fortunate pitchers in all of baseball this year. His Stuff+ is a mediocre 70 rating, and his command based profile isn't even supported by elite walk rates in the minors.

There's always a few pitchers who outrun the regression monster, but even among groundball pitchers, Elder is far from elite at producing extreme ground ball rates and launch angles. You compare him to his peers and you can see where Elder will start to fall off.

The stuff won't generate many whiffs (20th percentile K rate and 40th percentile whiff rate) and any regression in his ground ball rate will lead to a lot more runs allowed.

Note on Alek Manoah: Manoah only made one start back from his demotion to the minor leagues, against Detroit. The final stat line looked really impressive with eight strikeouts and no walks with just one run allowed, but there's almost nothing in the underlying profile that makes me believe he figured out his issues. The Stuff+ on the fastball and the slider were both below average in the Detroit start.

Unless he solves the slider and makes it good again, he's nothing more than a league-average starter at best. I'm not putting him on the fade list because the market solidly downgraded him prior the Tigers start, but wouldn't bet on him either.

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