The Coors field altitude means runs galore. The 2018 Houston Astros did not lose any key pieces and their offense should be historically good. Betting without understanding the full picture is a quick route to an empty bank account. The Colorado Rockies home games have gone under in 15 of their 23 home games (65.2 percent). The Houston Astros are the MLB leaders in participating in games in which the under is a profitable bet (33-21-4, 61.1 percent). The MLB is a third of the way through the season and now is the time to identify sustainable run total under trends.

Key Stats of the MLB Leading Under Teams

Rank Team Under % Under Record ERA Rank Team xFIP Runs Per Game wOBA BABIP
1 Houston Astros 61.1 33-21-4 2.67 (1) 3.17 (1) 4.95 (1) .325 (6) .307 (4)
2 Colorado Rockies 60.8 31-20-5 4.40 (22) 4.01 (12) 4.20 (20) .310 (18) .289 (22)
3 Milwaukee Brewers 60 29-20-5 3.47 (6) 4.02 (13) 4.30 (14) .315 (13) .299 (10)
4 St. Louis Cardinals 59.2 29-20-5 3.58 (9) 4.11 (17) 4.39 (12) .311 (17) .291 (19)
5 Washington Nationals 58.5 31-22-2 3.23 (2) 3.59 (3) 4.36 (13) .317 (11) .276 (28)

Colorado Rockies

The first step in analyzing the stats above is to isolate the Colorado Rockies. The four other teams are in the top ten in ERA which is a large contributor to the under trend. The Rockies are unique because of the perception of their home field.
Coors Field has always been a batters dream come true. In 2016 and 2017 the Rockies led the league in runs scored at home. In 2015 they were second in the MLB. That has coincided with a bottom two finish in home ERA each of those three years.
In 2018 the Rockies pitching staff is still performing poorly at home (29th in the league). However, the offense is not the same as it has been in previous years. In free agency, the Rockies opted to sign Wade Davis, acquire Bryan Shaw and retain Jake McGee to bolster the bullpen.

It has been well documented on the Bang the Book podcast that the Rockies offense has been unimpressive. It is a very top heavy lineup anchored by Nolan Arenado and Charlie Blackmon. Games at Coors Field are going under 65.2 percent of the time. When the Rockies are on the road the under is cashing for bettors 57.1 percent of the time.

Examining the Rockies ERA to xfip discrepancy shows the Rockies pitching staff could pitch even better for the rest of the season. Xfip factors fly balls to a league average homerun ratio so playing at Coors field lessens the validity of the xfip discrepancy because flyballs will always convert to homeruns at a higher rate. However, with a young pitching staff I expect the runs allowed to decrease for the Rockies.

On the offensive side there is not a lot of room for growth. They just lost a commonly used clean-up hitter in OF David Dahl, who is out with a broken foot. The Rockies do get Utility player DJ LeMahieu back, but with Ian Desmond hitting well below league average this offense will still lack significant punch. I will be playing a majority of the Rockies games under the team total until the market adjusts or the Rockies offense shows improvement.

Houston Astros and Washington Nationals

Plain and simple the Astros and Nationals have two of the best pitching staffs in the MLB. There is no debate about this. The Houston Astros rotation was not expected to be this devastating, but their ability to prevent runs is the sole contributor to the run total under trend. I expect the market to adjust, but public bettors love playing overs and with an exciting lineup I find it hard to believe that money will stop flowing in for Astros games.

With some of the Astros pitching out of their minds it is possible this trend is less profitable over the rest of the season. With the Astros already leading the league in runs scored, the pitching staff is the main variable to keep an eye on. Until the regression hits, I will be looking to play unders for games with the Astros involved.

The Washington Nationals are a team I will be looking to take the over in very soon. The starting rotation is unbailable, but they have a lot of offensive weapons who should be returning soon. 2B Daniel Murphy should be returning next week, and 3B Ryan Zimmerman and OF Adam Eaton are nearing their rehab assignments.

If you add the returning stars with the incredibly unlucky .276 Batting Average on Balls in Play (BABIP), there is a strong possibility we see an over trend from the Nationals for the rest of the season.

Milwaukee Brewers and St. Louis Cardinals

There is not too much to break down with these teams. With regression signs in the ERA and xFip discrepancy there could be more runs allowed from both pitching staffs. Both teams also rank in the bottom half in BABIP so I also expect them to score more runs than they have. I will be staying away from both of these teams in terms of having a lean to a run total side based on the data.

To recap, I will be continuing to play Colorado and Houston unders. As for the Nationals there could be some great late season over run total value. The Brewers and Cardinals are teams to keep an eye on. Injuries or player development could contribute to creating value on either side, but for now I do not have a lean.