Author: Mike Pastuovic (michaelpastuovic2023@u.northwestern.edu), Weinberg ’23

Coors Field is considered the most unique ballpark in Major League Baseball, with respect to its impact on gameplay. The high altitude (and consequently thinner air) in Denver causes baseballs to fly significantly farther in Coors than they would in a typical environment. Coors Field has routinely led MLB in Park Factor (PF) since the stat began being calculated. There are various methods of calculating Park Factor, with the common goal of deciphering the effect that a ballpark has on teams’ scoring output. A PF over one benefits hitters, while a PF below one benefits pitchers.

Rockies’ executives must take a unique approach to roster construction and identify players whose skill sets are well-suited for Coors. With that in mind heading into 2018, the front office bet that aggressive spending on the back end of their bullpen via free agency could lockdown otherwise high scoring games and take pressure off their young rotation. The Rockies spent a combined $106 million on Wade Davis, Bryan Shaw, and Jake McGee. These were very unsuccessful moves, to say the least. None of the three recorded a single season with a sub 4 ERA following their deals, and are all no longer with the organization.

Evidently, identifying talent that will succeed in this environment is a unique challenge faced by the Rockies front office. A similarly difficult undertaking for the other 29 franchises is determining how longtime Rockies will perform when they are not playing half their games in the best hitting environment in MLB. Execs around baseball have certainly had to contemplate how Nolan Arenado’s game would translate outside Coors Field, following his public discontent with Colorado’s ownership and front office. The discrepancy between Arenado’s output at the plate inside and outside Coors is particularly jarring, as he has a career .985 OPS at Coors and just a .793 OPS on the road. While still well above average, a player with a .793 OPS should and is viewed quite differently than one with a .890 OPS (Arenado’s total career OPS). Accurately predicting Arenado’s offense production if/when he is no longer a Rockie will be the focus of the remainder of this article.

I first want to preface this by saying that Nolan Arenado is undoubtedly one of the best third basemen in baseball. He is a plus plus defender, with unbelievable athleticism, great arm talent, shortstop range, and one of the quickest first steps in baseball. Entering his age-30 season, Arenado is 7th among all active players in Baseball Reference’s defensive Wins Above Replacement (dWAR) statistic. Each player above him on the list is older. 

The purpose of the upcoming discussion is to hypothesize how Nolan Arenado would profile at the plate over 162 games in more neutral offensive conditions. The conclusion will not be that Nolan Arenado is an average hitter, with all of his accolades a result of “Coors”. Based upon park adjusted statistics, Arenado is on a borderline HOF pace. 

Baseball Savant’s xwOBA (Expected Weighted On-Base Average), which began being calculated in 2015, is based upon launch angle and exit velocity, not affected by BABIP (Batting Average on Balls in Play) luck or ballpark environment. Looking at the differences between Arenado’s xwOBA and wOBA (an outcome driven statistic, set to the same scale) throughout his career can give us insight into how much he has benefited from playing in Coors. 

Year	wOBA	xwOBA	wOBA-xwOBA	MLB Rank
2015	.371	.345	.026	28
2016	.386	.352	.034	9
2017	.395	.371	.024	24
2018	.391	.351	.036	2
2019	.392	.349	.043	2
2020	.303	.275	.028	50

As seen above, Arenado has seen considerable discrepancies between outcomes expected based upon contact and launch angle and his actual results. This suggests that Nolan Arenado has uniquely benefited from his home ballpark, as he is consistently near the top of the MLB in wOBA – xwOBA. If Arenado were to play in a more neutral environment, we would expect this number to be closer to zero. It is fair to predict that the third baseman’s wOBA would drop .025 to .035 to be more in line with his xwOBA, a quite significant decrease.

Another valuable task could be to look at former elite Rockies and see how their numbers translated when they left the Rockies organization. Unfortunately, we are left with a set that is pretty critically limited considering that the franchise was founded in 1993, with Coors Field opening two years later. There actually have been a good number of elite hitters that have spent a large portion of their career in a Rockies uniform, however. Todd Helton, Larry Walker, Troy Tulowitzki, Carlos Gonzalez, and Matt Holliday are among the most notable.

Todd Helton is not helpful for this purpose, as he was a career long Rockie. Larry Walker is not particularly helpful either, as he came to Denver from Montreal as he was entering his prime, and was far removed from it when he left for St Louis. Shortstop Troy Tulowitzki had many injury problems after leaving the Rockies, so it is unfair to predict Arenado’s potential outside of Coors based off of his career. Carlos Gonzalez was also past his prime when he left the organization. The best comp for a potential Arenado departure is pretty clearly Matt Holliday. The left fielder left Colorado before his age-29 season (2021 will be Arenado’s age-30 season) and continued to put up strong numbers through the rest of his prime in St Louis. His numbers at the plate as a Rockie are pretty comparable to those of Arenado through the beginning of his career, so it is interesting to use him as a basis to predict Arenado’s future production if he were to leave.

wRC+ (Weighted Runs Created Plus) is a statistic that measures offensive production, controlling for ballpark. The league average wRC+ is set to 100, and a 110 wRC+ can be interpreted as 10% better than league average. Because this statistic is park adjusted, we should expect players’ home and road wRC+ to be relatively similar. However, this has not been the case for both Holliday and Arenado’s Rockie careers.

Holliday consistently had significantly more impressive wRC+ output at home in Coors from his age-24 to age-28 seasons, before leaving for a brief stint in Oakland. The same has been true for Arenado; in each of his eight seasons, his home wRC+ has been greater than his on the road. Again, wRC+ takes into account that certain ballparks (like Coors) are better hitting environments than others, so it is certainly interesting that these two all-star hitters have consistently recorded better wRC+ seasons at home throughout their Rockies careers. 

It now becomes reasonable to investigate the hypothesis that playing 81 games inside the unique Coors Field hinders players’ success on the road. The could be for a number of reasons: lower confidence playing in more normal conditions, different plate approaches, and pitchers attacking differently with the environment in mind, etc.

As seen above, both players had extremely large Home/Road splits at times during their Rockies careers. This can lead one to the conclusion that maybe these players are not that great of hitters, just benefactors of circumstance. The rest of Holliday’s career as a Cardinal largely puts this narrative to bed.

When looking at Holliday’s wRC+ numbers outside of Coors over his career, he was able to improve on already impressive numbers and have an extended prime of being one of baseball’s best hitters. It is likely that his performance outside of Coors as a Cardinal was assisted by no longer having to make the difficult mental and physical adjustments of hitting in such different environments on a series to series basis.

For these reasons, I am very optimistic that Arenado will continue to improve his production outside of Coors Field if he is moved to another club. I almost entirely discount his poor 2020, with the 48 game sample not being particularly significant or at all in line with his previous seven seasons.  

Nolan Arenado may struggle to improve upon raw numbers like his .315/.379/.583 slash line from 2019 if he no longer is a Rockie, as his previously discussed wOBA would be likely to converge towards his more modest xWOBA. However, the fact that Arenado has hovered around a 115 Road wRC+ in recent years tells us he will at least be very productive at the plate. Matt Holliday’s very comparable career arc suggests that Arenado could very well improve upon that, potentially being a consistent 125-130 wRC+ player in another uniform. When you pair these types of numbers at the plate with his elite defense, it is not hard to see how Nolan Arenado could end up in Cooperstown one day. He will be well worth the $199 million he is due over the remaining six years of his extension, and should not cost a crazy amount of prospect capital for teams willing to take on the money, as the Rockies are eager to shed payroll following large losses from COVID-19.

All Statistics used via Baseball Reference, Baseball Savant, ESPN, FanGraphs, Swish Analytics