Since 2018, the difference between the Phillies’ home and road records has been baffling:
At home, they’ve won at .590 clip (a 96-win pace over a full season), the 8th best home record in MLB.
On the road, their winning percentage has been .395 (a 64-win pace), the 24th ranked road record.
If we compare the two percentages, they have won at home 150% as often (aka 50% more) as they’ve won on the road.
We’ll multiply this by a 100 to make life a bit easier, and call it a home field advantage (HFA) of 150.
(We could just as well compare the home record to their overall record, and the numbers would be smaller but comparisons to the league or other teams wouldn’t change).
Since 2000, the MLB home teams have won at a .539 rate, vs. .461 for away teams:
That translates to a home field advantage of 117 (i.e. .539/.461, times 100):
Note that this fluctuates from year to year, as low as a .524 W% (110 HFA) over this period, and as high as .559 (127 HFA).
In 2020, without fans in the stands due to Covid, the question of home field advantage arose. The expectation was generally that HFA would shrink without fans, and the main question was by how much. In other words here was a real world experiment to show how much of a team’s HFA is due to the fans, as opposed to other factors, like sleeping in one’s own bed, not going out on the town as much, etc.
So it was an unexpected result last year, when without fans in the stands, HFA actually went up — home teams won at a .557 clip, or a 126 HFA. Maybe the restrictions placed on traveling teams hurt them more than not having fans hurt the home teams. Or, since it still wasn’t as high as in a typical season like 2010, maybe it was nothing more than normal variability. Whatever the reasons, it left the whole “impact of fans” question without much of an answer.
Then this year, as most teams started with limited capacity and then gradually allowed bigger crowds, league-wide HFA has dipped, though it’s still above the average since 2000: .547 W%, and a 121 HFA.
That’s MLB as a whole, and so let’s see how the Phillies look over this time.
Individual teams will tend to have a lot more variability, since the samples are only 1/30th the size.
The Phillies so far over the entire period of the 2000s, have had less of a home field advantage than the average: 115 vs. 117.
For many years, before, during, and a year after their “continued success”, their HFA was less than the average, year in and year out. From 2004 through 2012, they won almost as much on the road (.548, highest in MLB), as they did at home (.567, 8th highest). That’s only 3% more at home, i.e. a 103 HFA, which was by far the lowest HFA in MLB over that 9-year period.
Since 2013, they’ve had the 2nd highest HFA in MLB, at 135, just behind Colorado’s 136. While they’ve struggled over this period to the tune of the 2nd worst record in baseball overall (thank you Marlins), they’ve still managed to send the fans home happy 51.7% of the time, the 19th best home record in the majors. See table at the bottom for more.
The graph below again shows the HFAs for MLB overall, and for the Phillies, but adds in the highest and lowest for each year.
Note that just as team samples will have more variation than the league overall, 60-70 game team samples will also fluctuate more than full seasons. That, at least in part, explains the spikes in 2020-21.
So how unusual is the Phillies recent multi-year run of very high HFA? Since 2018, they’ve played 450 games, or almost three full seasons’ worth.
We can go back and see how common or rare the Phillies’ splits are over that large a sample. To keep the math simple, we’ll look at moving 3-year windows, which are typically 486 games, so if anything might be slightly less variable than 450, but probably not by much.
Below are 3-year average HFAs, starting with 2000-02, and advancing year by year to the present.
Again, the Phillies’ HFA is the lowest, or at least, very low, from the mid-2000s to the early 2010s. It then climbs to average-ish through the mid-2010s, and finally among the highest in MLB in recent years, including 2017-19 and 2018-20 when they had they highest HFA in MLB.
But what this also shows is that HFAs that high, while not common, are also not that rare. The Rockies in particular perennially have done much better at home, but also teams like the Rays, Pirates, and Orioles have had 3-year HFAs as high or even higher.
The fact that the Phillies’ HFA was very low when they were good and has been high lately begs the question as to whether it’s correlated to overall records. However year-by-year correlation between record and HFA is low, at 0.27. And over three-year periods, correlation is a very low 0.13.
And anyway, while the Phillies haven’t met expectations over these recent years, they’ve been more middling than bad.
What’s going on?
As to why this is happening, or when it’s going to get turned around, we have no answers here, but possible areas for more study:
- performance in 1-run and other close games
- differences in home vs. road performance by parts of the team: hitting, fielding, starting rotation, bullpen
Cursory looks show that in hitting, starting pitching, and the bullpen, the team not only did worse on the road than at home (that much is to be expected), but they also ranked lower in every aspect among all teams’ away stats, than they did among all teams’ home stats.
Maybe there are specific reasons in the makeup of this team, or maybe it’s random and it will turn around on its own.
Until it changes though it will be that much tougher for this team to mount any kind of run at the postseason.
Source for all home-away records: Stathead at baseball-reference.com
b/(w) means better or worse: for example the Phillies have won 6 fewer games at home (and won 6 more on the road) than they would have if they had the average home field advantage of 117.