Nolan Arenado Will No Longer Call Coors Field Home

Every season, I hope a superstar joins the Rockies, or one of their better hitters gets shipped out or signs elsewhere. It simply hasn’t happened very often, but it’s fun to see how the most unique park effects in baseball influences or has influenced the hitter’s results. We now get another chance to learn about the Coors Effect. This time with Nolan Arenado, who was just traded to the Cardinals. The challenge here is that Arenado played through a shoulder injury that ultimately resulted in an injured list stay. We don’t know exactly how long it affected him and can’t possibly quantify its exact effects. So if he improves significantly from last year’s .308 wOBA (and he certainly should), how many are going to conveniently ignore his health and claim the Coors Effect is a myth? Anywho, it’s something to remember, so let’s now compare the park factors for each park and how Arenado’s projection should be affected.

Surprise, surprise, it’s a near rout for Coors! Let’s start at the beginning.

What is perhaps not as discussed is Coors’ effect on non-home run hits. Look at those hit type factors! That’s the highest right-handed singles factor in baseball. Busch actually inflates singles as well, but barely. So this park switch represents a huge dropoff. That should directly influence BABIP, which is bad news for Arenado. Amazingly, even with Coors boosting his BABIP in half his games, Arenado’s career mark stands at just .299, which is marginally better than the league average. His career high mark sits at .320, which is solid enough, but perhaps a bit low given Coors’ BABIP-boosting abilities. You would think one year every batted ball would fall and he would really benefit from Coors, but his Away marks offset the Home mark enough to bring down his seasonal BABIP marks.

If you thought the gap in singles factors was large, check out doubles! Coors is far and away the best doubles park for righties in baseball. Arenado has been an exceptional doubles hitter throughout his career, so he could potentially lose a bunch of those as well, as Busch has actually suppressed that hit type. That’s going to reduce his extra-base hits, which means either those previous doubles become singles, or worse, outs. That’s another decline in BABIP, plus likely RBI and runs scored. Last, the biggest gap in factors is actually triples, where Coors is an absolute paradise, and once again the best park in baseball. This compares to Busch, which also suppresses this hit type. Unlike singles and doubles, this isn’t going to matter much for Arenado, who has hit just four triples over the past three seasons.

Let’s now move on to the home run factor, which is top of mind for fantasy owners. We all know that Coors is a home run hitting haven, and the park factor bears that out. Our latest park factors show that the park just edges out the second best park for highest right-handed home run factor. Unfortunately for Arenado, he’s moving to a park that reduces right-handed home runs. In fact, Busch had the fourth lowest factor in baseball in 2020. It’s rare you see a hitter switch from one extreme park to one of the most extremes on the other end. This is nearly the biggest difference you can find. Arenado’s career HR/FB rate stands at 15.8%, but has only posted a career best of 20.7%, even with the aid of Coors Field. Clearly, a move from the league’s best home run park to one of the worst may take a significant bite out of his HR/FB rate.

Next, we move to the plate discipline result metrics, walk and strikeout rates. I knew that Coors reduced strikeouts, but had no idea that Busch did too. So those are even and the park switch shouldn’t have an effect here. One of the skills that has made Arenado so good is his better than average strikeout rate, combined with his power. It’s the ultimate skills package, as many hitters have to choose between avoiding strikeouts or hitting for power. Coors also inflates walks, while Busch suppresses them. Arenado hasn’t been a big walker throughout his career, as he’s just once posted a double digit mark. The park move will make it more difficult for him to achieve his second double digit walk rate.

Last, we find the batted ball type factors. As I’ve said in the past, there’s no “good” ground ball and fly ball rates, so those factors are not highlighted. There certainly is a “good” line drive rate, as the higher the mark, the better, but both inflate the batted ball type by the same amount. I knew Coors inflated line drives, but again, had no idea Busch did too. At the end of the table is IFFB, or pop-ups, which strongly favors Coors. The park dramatically reduced those, while Busch has actually inflated them. Arenado has often struggled with pop-ups, made worse by his high fly ball rate. All those flies and pop-ups are one of the main reasons why his BABIP has been so mediocre. It’s crazy that he still hit so many pop-ups given his pop-up reducing home park. The move to Busch certainly won’t help him improve.

Without even looking at his home/road splits (which are deceptive, since Rockies hitters struggle more than other hitters on the road due to having to adjust to how pitches move at home versus away), it’s fairly obvious that this trade results in a massive hit to Arenado’s projection. Literally every metric is going to take a hit, including BABIP (and resulting batting average), walk rate, and HR/FB rate. I won’t know how much of a fall this translates to in terms of projected dollar value until I update my projection and run my dollar values, but I’m curious if the market is going to properly adjust or if he’ll end up overvalued. Of course, the health of his shoulder might be even more important after finishing the worst year of his career since his 2013 debut. That’s something we could only speculate about.