If you build it, will they win?

Take a minute to think of some of the most pleasant surprises in the MLB standings this season. Which teams came to mind? The Colorado Rockies, the Milwaukee Brewers, and the New York Yankees?

Now think of the reverse, the biggest disappointments. Who came to mind this time? The San Francisco Giants, and the New York Mets?

Now think about the home stadiums for each of those five surprising teams. The Rockies, Brewers, and Yankees play in stadiums that are thought of as some of the friendliest confines in all of baseball, while the Mets and Giants play in far more cavernous home stadiums. Could it be that, in this era of home runs, having a home stadium that plays into the hands of home run hitters is a benefit on a team-wide level?

Well, the previous list was obviously some extremely anecdotal evidence. Here at Beyond the Box Score we don’t like to deal in the business of anecdotal evidence, so let’s take a bit of a deeper dive into the numbers to see if there is some sort of correlation between homer-friendly home stadiums and surpassing preseason expectations in this, the era of the home run (and possibly juiced baseball).

Well, that is certainly an interesting chart. Using ESPN’s 2017 MLB Park Factors (sorted by home runs specifically) and FanGraphs playoff odds graphs, there certainly does seem to be a bit of a pattern.

The Diamondbacks and the Yankees, two of the top three teams in terms of biggest jumps in playoff odds, are also two of the top three in terms of home run factors in their home stadiums. At the other end of the table, the Mets and Giants rank 29th and 30th, respectively, in both change in playoff odds this season as well as home run park factors.

Now the correlation isn’t perfect, and when the numbers are run, it isn’t even necessarily significant in a statistical sense. Those two columns have just a 0.47 correlation coefficient. That is a ways from the point where we can guarantee a real relationship, but there are a few points that need to be made in regards to the data.

Let’s take a look at the bottom of the table. The Red Sox and Royals are a pair of teams that skew the results a bit, as they rank 10th and 17th in terms of success in relation to their preseason odds. If the premise is that teams with less homer-friendly stadiums should be struggling more in regards to their preseason predictions, both clubs should be struggling more than their ranks above would suggest.

This is where the FanGraph odds can be a bit tricky. One has to imagine that if you asked any Red Sox fan — and certainly if you asked any Royals fan — they would be a bit disappointed with the current campaign. The Sox came in as the AL favorites in the mind of many pundits and their preseason playoffs odds of 80.3 seemed a bit low before the season. They are also currently sitting behind the Yankees in the AL East, and while they have the third-best winning percentage in the AL, their status as favorites in the junior circuit has undoubtedly been handed over to Houston.

As for the Royals, the projections always hate them, so there was only so much further they could go down in playoff odds. Their current standing of fourth place in the AL Central is a disappointment for many fans who saw this as a last gasp at relevancy before the team has some serious questions to answer in free agency.

There’s also the matter of playoffs odds being able to only move so much at each end of the spectrum. The Dodgers (fifth-highest home run factor home stadium) have made strides in terms of the odds of making the playoffs (at least according to FanGraphs), but their odds can only get so much better given that they started the season with 95+ percent odds of making the playoffs.

Finally, playoff odds are league- and division-dependent. Part of why the Angels playoff odds have dropped so much (in addition to losing Trout for 6-8 weeks) is because the Astros are running roughshod all over the AL West, with a double-digit lead in the division already. The homer friendliness or un-friendliness of Angel Stadium can’t do much about that.

With that in mind, let’s take a slightly different tack and use change in FanGraphs’ expected wins rather than playoff odds. There’s still a bit of league- and division-dependency because of the nature of an MLB schedule, but it’s less of an effect and there’s more room for flexibility at the ends of the spectrum. (The Padres going from 0.1 percent to 0.0 percent odds of making the playoffs doesn’t tell us much, but if they move from 66 expected wins to 50 expected wins, this will pick it up.)

Once again there are the Diamondbacks and Yankees at the top and Giants and Mets at the bottom, supporting the possible claim that homer-friendly ballparks are helping teams outperform preseason expectations, but there seem to be a lot more holes in that logic with this chart.

Cleveland’s struggles become even more stark, and Tampa Bay and Cincinnati are more noticeable as average parks supporting surprising teams. The correlation coefficient drops to 0.26 with this chart, a significant drop and now a long ways from significant.

The Phillies can be excused as a team that is simply in rebuilding mode, a team whose stadium wouldn’t matter one way or another, but wasn’t that what most folks said about the Brewers before the season? If the Brewers fast start is going to be used as anecdotal evidence of a relationship between homer-friendly stadiums and surpassing preseason expectations, writing off the Phillies seems like twisted logic.

Here’s one final chart:

This chart is straightforward, comparing home stadium home run park factor to rank in standings from 2014 and 2016 — i.e., before and after the massive jump in home runs that has taken over the league. The 2016 season was used because it had a similar (albeit slightly less-intense) home run environment, but it has the added benefit of being a full season’s worth of data.

It is certainly notable that in both seasons, having a homer-friendly home stadium actually had a slightly negative correlation with winning percentage rank. However, that negative correlation was much greater in 2014, and in 2016 the correlation was basically zero.

While that may seem to be the final nail in the coffin, it is worth noting that so far this season, the winning percentage to home stadium home run factor correlation is up to 0.38. This relationship is still not approaching the realm of significant, but it is a large leap forward from seasons past, and a potential sign of a trend towards homer-friendly stadiums having a more positive impact on winning.

All stats are current through June 11.

Jim Turvey is a fresh, new face to Beyond the Box Score. He also writes for DRays Bay, Call to the Pen, RotoBaller, and Insider Baseball. You can follow him on Twitter @FantasyBaseTurv.