It’s been one of the enduring mysteries of the 2019 baseball season. Why have the Chicago Cubs been so bad on the road?

There’s a chance for bettors to ponder that conundrum Wednesday night, when the Cubs visit the Philadelphia Phillies in a nationally televised battle of playoff contenders (ESPN, 7 p.m.).

The market, and sharps in particular, have been waiting for Chicago to “regress” toward expectations with better results. Baseball isn’t supposed to have teams that play at the level of championship contenders at home, but rebuilding tankers on the road. If you look through home/road splits in today’s full MLB standings, you’ll see the Cubs’ difference really has been that extreme.

A deep dive into team and player statistics shows pitching has been the biggest culprit. Entering the week, Chicago’s “road only” pitching ranked in the bottom third in ERA and WHIP, and subpar in strikeouts and K/BB ratio.

The starting rotation largely has stayed intact all season. None of the five main arms has managed to achieve both an ERA below 4.00 and a WHIP (walks plus hits per inning pitched) below 1.40 away from Wrigley Field.

Cole Hamels (3.91 ERA, 1.43 WHIP): Hamels is the only starter under four in road ERA, and that’s in danger with a scheduled start in the Philadelphia bandbox. His disappointing WHIP suggests trouble ahead versus quality offenses.

Yu Darvish (4.14 ERA, 1.13 WHIP): The only Cubs starter with a good road WHIP. There will always be fears that he’ll start tipping his pitches again, making him a dicey investment for bettors during a pennant chase or the playoffs.

Jose Quintana (4.34 ERA, 1.41 WHIP entering Tuesday night’s start): Those are generic “innings muncher” numbers, which are only acceptable at the back of a contending rotation.

Jon Lester (4.86 ERA, 1.41 WHIP): Lester was a half-a-run worse than Quintana entering the week.

Kyle Hendricks (5.16 ERA, 1.51 WHIP): Disaster! You’re going to try to win playoff games on the road at Atlanta or the Los Angeles Dodgers with that?

A potential factor in this year’s dynamic is Wrigley Field itself. It’s been one of the best pitchers’ parks in baseball in 2019, reducing scoring by 11 percent and both home runs and doubles by 15 percent. There haven’t been many day games with the wind blowing out forcefully. Prevailing winds in the evening (plus mediocre visibility) help pitchers.

Though, it has to be pointed out the Cubs offense isn’t showing much of a ballpark influence (within fractional arm’s reach of five runs both at home and on the road).

Maybe Cubs pitchers have figured something out about maximizing their skill sets at home. Maybe it’s a fluke. But, it’s probably not a fluke that nobody in the Chicago rotation is thriving this deep into the season at a cross-section of visiting parks. Bettors should be wary of investing in this team on the road against quality offenses through the rest of 2019.