How Will the MLB's New Rules Affect Early Season Baseball Betting?

MLB's new rules have greatly improved offense in Spring Training — but what about once the real games start? We've asked some of the top books around how they're preparing... and also have a market that is poised to offer plenty of early value.

Last Updated: Mar 29, 2023 8:36 AM ET Read Time: 4 min
Connor Joe Pittsburgh Pirates MLB
Photo By - USA TODAY Sports

Baseball will look a little different this year with bigger bases, pitch clocks, disengagement limits, and a kibosh on infield shifts. MLB’s heavily-hyped new rules have already been a big hit in Spring Training, where they’ve led to an uptick in offense: Scoring has ballooned by 0.4 runs, hits on balls in play are up 23 points, and stolen base attempts have increased by 50%. It's easy to see how left-handed hitters and speed merchants will be among the players most likely to appreciate these rule changes.

These numbers are noticeable, but are sportsbooks ready to make big adjustments to MLB odds on small sample sizes from games that mean very little to the teams playing them? We reached out to representatives from some of the biggest operators around as well as one of the best baseball projectionists in the biz to find out.

New MLB rules for 2023

The three biggest rules we're looking at are:

Pitcher restrictions

  • A 30-second timer between hitters for the first pitch of an at-bat
  • A 15-second timer between pitches in the same at-bat (20 seconds if there are runners on base)
  • Automatic ball if the pitcher does not throw by the time the clock expires
  • Batters must be set by the eight-second mark on the timer, otherwise an automatic strike

Defensive shift limits

  • All four infielders must stay on the infield when the pitcher is on the mound (cannot touch outfield grass)
  • Infielders cannot switch sides: There must be two guys to the right of second base (3B and SS) and two to the left (2B and 1B)
  • Outfielders can shift into extra infielders
  • If rules are broken at the time of the pitch, the hitting team either receives an automatic ball or accept result of the play (in the event it was a hit)

Bigger bases

  • Bases traditionally were 15 inches square, but are now 18 inches square
  • Results in a 4.5-inch reduction in the distance between first/second base and second/third bases
  • Home plate remains unchanged

Sportsbooks are taking a wait-and-see approach

Oddsmakers have been crunching the numbers this spring, but remain uncertain if big offensive increases will continue into the regular season.

“We have certain expectations and hypotheses about how the rule changes will affect the results, but we can’t quite be sure about their effects until the regular season actually kicks off,” stated the FanDuel Canada trading team when asked how the rule changes will affect how they’ll set lines during the regular season.

“The new rules have been enacted in Spring Training, but those results are pretty inconclusive as teams aren’t necessarily trying to win and are still tinkering with and adjusting to the new rules," FanDuel said. "Once the regular season begins, we will be monitoring offense across the league very closely, and based on these early results we’ll adjust as needed.”

That's the same approach being taken by the SuperBook at the Westgate Las Vegas. "At this time, we haven’t made any adjustments," explained Vice President of Race and Sportsbook Operations Jay Kornegay. "We’re going to monitor the shift ban, larger bases, and pitch clock to see if it has an effect on the scoring. We think it will be minimal at most. We also want to see if the pitch clock will have a negative impact on certain pitchers. We’re playing it by ear."

But what about specific markets? Are there any that the books think will be bigger liabilities because of the changes?

“Ideally, if our pricing is right, we won’t have many markets that carry significantly more liability than others,” added the FanDuel Canada trading team. “With that being said, it’s possible that customers see the rule changes and bet on increased offense early in the season, anticipating that offense will significantly increase. That could be game totals, team totals, pitcher prop Unders, or hitter prop Overs to name a few."

"However, once the customers and FanDuel both gather more data from the regular season, we’ll have more confidence in our pricing as it may pertain to the new rules, and as such we don’t expect any specific markets to carry significantly more liability.”

Phill Gray, head of trading operations at Sports Interaction, is taking a similar strategy towards pricing.

“A lot of it will be a wait-and-see. Obviously, Spring Training won’t give us the data to immediately make any wholesale changes. The assumption that scoring could be higher can actually go both ways in my opinion," said Gray. "The pitch clock, for example, will create less time for a pitcher to prepare, and also less time for the batter. That could even out in a lot of situations and actually, just leave the scoring rate as it is.”

Kornegay says the SuperBook at Westgate Las Vegas is also monitoring the situation closely to see what happens early in the season. "Like in the past, going into a season, we didn’t know MLB was using a 'juiced' ball until we got into the regular season and then adjustments were made," he said.

Sportsbooks and some modelers are at odds

The public’s perception of the possible increase in scoring might not move the needle for some of the most experienced traders in the industry, but what about when those calls are coming from one of the best baseball projectionists and modelers in Derek Carty?

Carty’s baseball projections can be found across the baseball world in DFS, fantasy, and betting circles and his BAT projections are a staple at Fan Graphs. THE BAT X creator thinks the numbers we’re seeing this past month will translate to the regular season and uses some solid data accumulated in the minor leagues where the new baseball rules were tested out to prove his points.

Projections suggest stolen bases will be on the rise

Some of the biggest things he’s projecting this season in the MLB is a 21% increase in stolen bases, which might even be modest when we saw a 32% increase in Double- and Triple-A once the rule was implemented.

“Obviously, the bigger base means a shorter path to being safe,” Gray adds when asked if he expects more money (liability) on certain markets. “Does 4.5 inches matter that much? We’ll definitely likely see more stolen-base attempts and the two-pickoff limit for pitchers will add to that. It could result in more stolen bases, but that could be lessened with the increase of attempts rising, the number of times players get thrown out should, as well.”

Carty does mention at the end of the thread that these numbers are just estimates and that “we’re dealing with imperfect data, making certain assumptions, and ignoring the possibility of unintended consequences.”

It’s a needed disclaimer, but thanks to pitch clocks, bigger bases, and pick-off limits, base runners will have a huge edge this season.

In addition to bases being 4.5 inches closer, pitch clocks will give base runners an edge because they know when a pitcher has to begin his delivery — and if the pitcher has already attempted his maximum of two pick-off attempts, that base runner can get very aggressive with primary and secondary lead-offs.

It might not correlate to a 10-12% increase in total runs scored, but it will certainly increase stolen base attempts... and for props that can range from +400 to +1,500 for a successful swipe, there is a lot of money on the line for who is right.

From what we’re seeing from the books, there could be a short window of opportunity for bettors to profit on stolen-base props. The best value could be with middle-tier players who can easily return profits much higher than home runs.

High stolen-base players will likely be the first to be adjusted in price but it’s the guys who stole 10 to 15 bags a season ago who could be returning 10 to 1 or better early in the season.

A successful base-stealer like Aaron Judge (16-for-19 in stolen bases in 2022) could be a great target, as well as Tim Anderson (13-for-13), Trevor Story (13-for-13), J.T. Realmuto (21-for-22), Jace Peterson (12-for-13), and Jose Altuve (18-for-19).

These players don’t immediately come to mind when bettors think of steals, but that’s a good thing when looking for value. They’ve already been successful with much tougher rules and now with a big advantage, could increase their output by 30-40%.

Bettors need to act fast before sportsbooks adjust

Carty is projecting steals across the board, so whatever avenue bettors go down to target stolen-base props, it’s all looking promising as these rules will benefit every player. However, if the swipes are on the rise, expect books to adjust quickly and accordingly.

Another edge bettors will certainly have is targeting slower pitcher-catcher combinations who were already susceptible to stolen bases before the rule change.

This will likely take longer if at all, to be priced into the stolen-base market, but we’ll keep that edge under wraps for now.

Written with contributions from Geoff Zochodne.

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