Baseball has seen a measurable drop in runs per game and home runs in 2021, but the shift in scoring has not impacted betting markets – at least not yet. But bettors remain wedded to their traditional default of favoring the "over" in Major League Baseball betting markets.

Through play on May 16 (1,196 games), teams have averaged 4.39 runs per game. In 2019, baseball’s last full season, MLB teams averaged 4.83 runs per game. There are five teams scoring more than five or more runs per game this year. At this point in 2019, there were 12.

Representatives from DraftKings, FanDuel and PointsBet told Bookies.com that their sports betting sites have made slight adjustments in their daily betting totals but there has been no determinant change in how run totals are set or in the overall numbers.

“We consider all statistical metrics in setting our lines in the MLB and have noted the decline, season to date," FanDuel spokesman Kevin Hennessy said. "That said, overall, it’s a small sample size and as a result, we have not made any material changes to our practices. We also haven’t seen any noticeable changes in the wagering behaviors of our customers.”

Here’s a look at overall runs per game for the 10 most productive teams in baseball in 2021 through the games of May 16 compared to the top 10 teams in the majors at the same point two years ago.

By the end of the 2019 season, a dozen teams had surpassed the 5-runs-per-game mark. The Yankees led MLB with 5.77 runs per game in 2019, while the Twins were second with 5.73 and the Red Sox stood third at 5.77.

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Home Runs On Decline In 2021

Home runs, too, are on the decline. MLB averaged 1.39 home runs over the full 2019 season. That number is down 19% this season to 1.13 HR per game after nearly 1,200 games.

“It's early in the season. We've got a long way to go yet and things will change. I believe things will change,” DraftKings Director of Race and Sports Betting Johnny Avello said. “There's fans in the stands, but we're not at full capacity. But if you look at the teams that are at full capacity, the Astros, they have more hits than many teams. Maybe the fans in the stands make a difference,”

In 2019, the slash line for all of MLB was .252/.323/.435. That marked a 58-point increase in OPS in just five years. The trend has reversed itself this season, the slash average slipping to .236/.313/.392.

Players embracing launch angle played a role in that increase, in addition to changes in the baseball. In 2021, MLB ordered that Rawlings loosen the tension on the first of three wool windings within the ball in an effort to lessen the distance balls could travel when hit longer distances.

The numbers – thus far – show a decrease in runs and home runs.

Betting numbers, Stats ‘Regress to the Mean’

Whether or not baseball will "regress to the mean" remains to be determined.

“There's no market consensus on totals being lower or anything. We are skewing them a little bit lower than they would be, but we don't want to over-adjust on that because data should always regress to the mean,” PointsBet Analyst Mike Korn said. "It's definitely something that is interesting this early in the season. I think it's more of something to look out for as the season goes on and as we build that data there."

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All of this information and more is factored into the daily run totals at your favorite legal sportsbooks. Some minor reactive steps have been taken when setting lines. But any data set used to set forward-looking trends is years into the making, not just 45 days.

“You'll get some guys that will say three years is enough data to start with. Then, you'll get the guys that want a ton of data and won't start to accept things that are happening from the data until you get to 10 years,” Korn said. "I think three to five years is a good point where we have enough information to where we can be predictive off that information that we're getting. We're not adjusting fully to what's happened yet because we don't think it's enough data at this point."

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Bettors Still Love The Over

A look at the game totals and betting handles on the over/under for more than 200 games played in the month of May thus far finds that oddsmakers are right on target when predicting the total number of runs per game. At DraftKings, 102 games have gone over the total while 100 have stayed under. Another 12 finished with a push or had no line.

In terms of overall handle, bettors continue to follow form and back the over. On average, 59.5% of the daily handle has been wagered on the over and 40.5% has been laid on the under.

(Daily totals and splits via DraftKings as of each game day.)

“Have we made adjustments? Yes. Some. You have to adjust to what's going on out there in the market, but if we did, it's not drastic, it's slight and we pay attention to it on a daily basis,” Avello said. “In general, bettors don't like to bet under. It's universal in most games. The feeling is, if you bet the over, you always have a shot. But if you bet the under, you could be out of it early. That’s just the way the better looks at it sometimes,” Avello said.

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Avello believes the decline in home runs is another contributor to the decline in overall runs.

Betting on baseball has mirrored baseball in terms of its near-complete reliance on analytics and immediate computation of in-game lines fed by stats updated in real time with each pitch.

It wasn’t always that way.

“We used to do a lot of things manually. Of course, we had a spreadsheet like Excel or something similar to that, but the way it's done today is totally different. There's a lot more that goes into it. So the number now is more precise on everything that's been going on,” said Avello, who has been associated with sports betting for more than 40 years and ran the Wynn sportsbook in Las Vegas for 13 years before joining DraftKings in 2018.

“You have to make slight adjustments because trends are temporary. Hockey was about goals scored in the first period. And the NBA was points being scored in the first half, and then the whole game,” Avello explained. “They weren't reaching the total number that was projected. But then everything seems to pick up as the season goes on. Things change. So that's why when you make your adjustments, they're minimal."

"Now, if it lasts through the whole year and the players are really pounding the way the trend has gone, of course, it gets drastic," Aviello added. "But, when I tell you that we're still writing 55 to 60% business on the over then, we don't need to make this drastic of adjustments.”

Throw 2020 Out Of The Mix

Any year-over-year statistical comparison in major league baseball – here and elsewhere – discounts the 2020 season. That COVID-19 hampered campaign lasted just 60 games.

To measure the absurdity of trying to compare 2020 numbers to 2021 numbers, one needs to look no further than the Boston Red Sox. Last year, the team went 24-36 over 60 games. This year, the Red Sox surpassed that win total 41 games into the season.

As far as 2020 goes, Korn and Avello agree that it was a one-off.

“Everything was different, the way that managers manage teams with putting players in and stuff. It was just a completely different year than what baseball is normally. I would say that it's more of a one-off type thing, and we have an asterisk next to next season in terms of using that data,” Korn said.

“Forget about 2020,” Avello added.

There’s little doubt baseball already has.

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