Alec Burleson has hit 47 fly balls at Busch Stadium this season with an average expected wOBA of .610 and an actual of only .397. Burly is getting absolutely ripped off by his home ballpark. Baseball Savant’s Park Factors calculation ranks Busch as the fifth most stifling park in baseball. It has been particularly tough for lefties over the last three seasons with only Tampa Bay and Seattle ranking as more difficult places to hit. Lefty power hitters are punished the most with a home run factor of 73, where 100 is average. Add it all up and it is no surprise that the Cardinals offense has been a bit flat at times. Despite an expected wOBA of .323 (4th in baseball), the Cardinals’ actual wOBA ranks 25th and their runs per game ranks 19th.
This gap in expected vs. actual production led me to investigate which Cardinals are being punished the most by the unfriendly confines of Busch Stadium. As I started getting into the data, the obvious secondary question arose: is the underperformance due only to their home park, or has there been a bit of bad luck too?
For this investigation, I will focus on wOBA and its various cousins, so I want to provide a few points of reference. The MLB average wOBA is .316 this season. wOBA is not park or league adjusted, but in a neutral environment, .316 would equate to a wRC+ of 100. wOBAcon is simply the wOBA on contact only, so it removes walks, strikeouts, and HBP from the calculation. The MLB average for wOBAcon is .364. The expected versions of these statistics (xwOBA and xwOBAcon) are calculated using exit velocity and launch angle. One of the limitations of the expected statistics is that they do not take into account the direction a ball is hit. More on that when we discuss fly balls.
The Cardinals have the tenth-best road offense in the league by wRC+, checking in at 101. Their home wRC+ of 89 ranks 27th in baseball. Remember, wRC+ is park adjusted. It is relatively unusual for a team to hit this much better on the road. Across MLB, teams hit six points higher at home than on the road (103 vs. 97), and the Cardinals are one of only four teams to have a reverse split of ten or more. I was curious if there were any teams that consistently hit better on the road, so I looked at the splits going back to 2021 and only the Angels have hit better on the road in the aggregate. The Cardinals have a normal 104 to 98 wRC+ home/away split over that time period. These facts alone lead me to believe that some of the Busch struggles can be attributed to bad luck.
This bad luck would likely be showing up in the Cardinals’ home/away damage on contact (wOBAcon) splits. The below table compares the Cardinals’ expected wOBA on contact to their actual results.
Sure enough, the team’s expected production on contact is similar home vs. away, but the gap on production at home pulls the overall wOBAcon down to .342, the second-worst mark in the majors. Cardinals hitters are underperforming their expected damage on contact at home by .037 points. For the sake of comparison, I pulled the same metrics for Cardinals pitchers at Busch. As a group, they are outperforming their collective xwOBAcon by .022 points. Going back to our park factors reference, Busch has suppressed wOBAcon by 6% over the last three years. Cardinals pitchers are getting that 6% benefit almost exactly, while the hitters have underperformed by 10%. While not conclusive, this does put a point in the “bad luck” column.
I do want to check in on the fly ball issue. Historically, the Cardinals have had teams that underperformed their underlying data because too many of their fly balls were hit to center and the opposite field. To illustrate the problem with this, I pulled data from Baseball Savant on every fly ball hit in MLB this year, broken out by direction.
Players or teams that pull the ball more frequently outperform their expected production (.611 expected vs. .858 actual). Opposite-field flies are measured fairly accurately, but fly balls in the middle of the field cause significantly less damage than the xwOBA formula projects due to deeper fences and more skilled defenders.
Poor directional distribution does not appear to be the driver of the Cardinals’ Busch Stadium woes; their percentage of pulled fly balls at home is in line with the major league average and their center-field percentage is below average.
Despite this solid distribution of fly ball direction, the majority of the Cardinals’ problems are indeed coming from fly balls. The major league average wOBA on fly balls is .425. The Cardinals’ average wOBA on road flies is a stellar .445. At home, the wOBA on fly balls falls all the way down to .355 (xwOBAcon of .454).
So, which players are feeling pain?
Not surprisingly, the three players with the biggest splits are all left-handed. As I opened with, Burleson has serious grounds for irritation with his home field. His pulled fly ball rate of 36% is well above average, which makes the lack of production even more frustrating. Wetherholt has had some bad luck as well. Only 21% of his fly balls have been to the pull side, but he is underperforming his expected stats on line drives by over .100 points.
Interestingly, none of the top right-handed hitters have had as much of an issue with Busch. I cut the chart off at 100 balls in play, but the rest of the righties have had horrible luck in small sample sizes.
It is easy to identify the players that have paid the highest Busch tax. Burleson in particular has been crushing balls all year without getting full credit for his awesomeness. Wetherholt is more of a mixed bag with his poor pulled fly ball rate, but he has already shown a remarkable ability to make adjustments at the big league level, so I am guessing he will get to even more pull power. Regardless, his luck on line drives is sure to improve and lift his stat line as well.
Untangling environment from luck is a bit more challenging, but I really do think this is an above-average offense. In the Statcast era, the Cardinals have underperformed their expected wOBA by .006 points. The current gap would be a new low-water mark for the franchise if the trends do not reverse. I focused on the contact side of the offensive equation in this article, but the Cardinals are also one of the best teams in baseball when not making contact. With the seventh-best BB/K rate in baseball and the most HBPs, their “damage” on non-contact outcomes is third in baseball. The fact that opponents at Busch are performing closer to expectations gives me hope that the offense can see some positive regression toward their expected stats.