Tuesday, August 31, 2010

The Cubs Home-Field Disadvantage: Is Day Baseball to Blame?

A few more night games might not be a bad idea.
Yesterday I looked at the Cubs' league-worst home-field advantage since 1970. Today I'm surveying the history of the Cubs at home since 1901. Obviously most of that (every year from 1914 on) is at Wrigley Field, but I threw in the numbers from before that as well simply because . . . well, because I have them.

Before I go any further, I just want to rehash a few main points from yesterday's post:
  • Home-field advantage is legitimate in Major League Baseball. Every year since 1901 the home team has won a majority of the games played in baseball (a .540 winning percentage since 1970).
  • A study of the 2004 MLB regular season showed that travel leading up to a game has no effect on win probability for either team.
  • The study also concluded that home-field advantage is statistically relevant only in games decided by one run.
  • Results over the years support that studies conclusion that home-field advantage matters the most in one-run games; the home team has a .608 winning percentage since 1970. The home team has still maintained an advantage in games decided by 2 runs or more (.511) or 3 runs or more (.518).
  • Since 1970, the Cubs have MLB's worst winning percentage (.577) in all one-run home games where their advantage should be the highest.
  • Explaining home-field advantage is considered one of baseball's most indiscernible mysteries.
  • The Cubs, like every team in baseball, have an advantage when playing at home, but theirs has historically been less advantageous than that of any other team.
Most people who care to argue generally take one of a few main positions in explaining the home-field advantage in baseball. The first is that the structure of the game itself favors the home team. They'll argue that having the last at-bat either allows the home team a strategic advantage in one-run games (they know exactly how many runs they need to score in the 9th) or that it simply creates the statistical illusion of an advantage (if the home team is tied or trailing in the 9th, they'll almost always win by one if they win at all, and they never have the opportunity to build on their leads after the 8th inning). 

Another main argument is that playing in front of the home crowd and hearing their cheers (or, adversely, boos) in a familiar environment gives the home team a psychological or emotional advantage that comes into play especially significantly in close ball games and dramatic situations. I'd expect this type of thing to be more observable in basketball and football where playing at home offers no advantage within the game itself. But I'd also expect that over time that type of thing would equalize from team to team.

The other main factor in discussing home field advantage is the field itself. Baseball is unique among team sports in that the field of play varies pretty significantly from venue to venue. Teams can then customize their teams according to their home park (or adjust the field to the team's strengths). It could be the spacious outfield at Petco, the speedy Astroturf infield at the old Busch Stadium, or the light mountain air of Coors Field. (Coors seems to have had the greatest impact on that front. The Rockies have a .652 winning percentage in the 339 one-run games in Denver, and there isn't a close second in recent history. Three teams are tied with .635.)

Like I said earlier, the average winning percentage in one-run home games since 1970 league-wide is .608. There are only two teams with winning percentages more than .030 points away from that mark on either side. The Rockies at .652 (+.044) and the Cubs at .577 (-.031). The Coors effect isn't really all that surprising, because the high altitude, you'd expect, requires an adjustment most visiting players need more than a few days to make. With Wrigley the most obvious explanation, the unique factor that comes to mind almost immediately, is the prevalence of day baseball. Is that really hurting the Cubs?

I think it is. I broke down the Cubs' record in those all-important one-run games at Wrigley by decade using the miraculous Baseball-Reference play index tool. I went by decades because it takes that long for a good 200+ game sample. The results almost speak for themselves, but I'll ramble on just for kicks.

Cubs Home-Field Advantage in 1-Run Games by Decade
1901-19096 of 1620012971.645.613.032
1910-19195 of 2423815484.647.611.036
1920-19297 of 1623514986.634.622.012
1930-19391 of 1621614967.690.629.061
1940-194914 of 16243136107.560.617-.057
1950-195915 of 16257145112.564.617-.053
1960-196910 of 2425115695.622.608.014
1970-197917 of 26255148107.580.599-.019
1980-198919 of 2624014496.600.615-.015
1990-199924 of 30251145106.578.606-.028
2000-201028 of 30265146119.551.614-.063
1901-201019 of 30265116011050.604.612-.008
1901-19413 of 16*939607332.646.618.028
1942-201030 of 301712994718.581.610-.029
*Of teams with at least 100 1-run home games in that span

As you can see, the Cubs enjoyed a pretty healthy home-field advantage compared to the rest of the league until the 1940s. Since then, they've only been above average in one decade. So what changed? 

Well, in the late 1930s, the starting time of baseball games began to change. By the start of the 1942 season, only 5 teams had yet to install lights at their parks, and by 1949 there was only one holdout remaining. That team wouldn't play a night game at home until August 8, 1988. Even now they play more day games than any other team in baseball, including all of their Friday home affairs.

Cubs home games have a uniqueness all their own. They play more night games than they used to, but the balance is still significantly different than the schedule of any other MLB team. That uniqueness is very likely costing the team wins. Since the 1942 season when most teams began playing night baseball, the Cubs have enjoyed a smaller-than-average portion of the built-in advantage appointed to every team in baseball. They went from a 2.8% better-than-average clip to a 2.9% dip below average.

Maybe it's more than just the day-baseball factor. Maybe it's their sub-par team facilities, too. Maybe it's just luck. But seeing as though the bad luck thing doesn't seem to want to go away, maybe the Cubs should address those other two distinctive traits and make the Wrigley confines a little more friendly to winning.


  1. I would consider myself an educated Cubs fan. And my educated theory is that the Cubs won't win a World Series until they leave Wrigley. There's plenty of argument to say that my theory is a crock, but based on the numbers you've provided and the fact that "a blind squirrel finds a nut every once in a while" I'm going to hold to my theory. You would have to assume that in the past 100+ years, there had to be one combination of players that would have won it all (1945, 1969, 1984, 2003, 2008). There hasn't been. The only constant amidst all the other variables has been Wrigley.

  2. I agree with B Dubz. I love Wrigley Field (it's a heck of a lot nicer than, say, the Oakland Coliseum) but the Cubs have never won a World Series in its existence. Kind of funny that most fans are more concerned with keeping a manual scoreboard and troughs than the fact that their team hasn't won in the entire lifetime of their beloved park.

    I do have a question or two though...one is statistical, in that we're going from a +2.8% to a -2.9% off average, and was wondering if that is actually statistically significant or if it's within noise. The other is whether too much day baseball really messes with a player...I imagine that if you prep for day baseball as a Cub you eventually get used to it, but I wonder if it's a body clock issue or the fact that the changing shadows and positioning of the sun would mess with a player's ability to read the ball out of the pitcher's hand, or to track fly balls if the sun were unforgiving...

  3. I hope your theory's dead wrong, but reality is tending to agree with you. I don't think these numbers by any means render it an impossibility, but it's safe to say Wrigley is not helping.

  4. Those are good questions, RC, and I'm not sure I can answer them. I'm no great shakes at standard deviations and that stuff, so I might need to find help to answer the first one. But as far as day baseball goes, I think it's more a matter of changing schedules so much. The shadows, sun, and other factors all affect both teams in the same way. Yeah the Cubs might be more familiar, but I doubt "getting used to" Wrigley is that big of an advantage.

    But the body clock issue affects the Cubs specifically in a unique way because only the Cubs have their schedule. Other teams for whom day games are more of a once or twice a week occurrence, the occasional extra day game at Wrigley is a small adjustment. For the Cubs, there's really no regular routine or rhyme or reason.

    I don't know why that would manifest itself specifically in one-run games at Wrigley, but if there's a psychological (or physiological) explanation to HFA, the body clock thing could come into play.

  5. Okay, here's my basic conclusion on the matter of significance: statistically, I don't think there's a high probability these results are accidental. Over the equivalent of ten full seasons represented in the data from 1942-2010, I can't imagine things getting much closer to a true representation of home-field advantage at Wrigley.

    But in terms of baseball significance, yeah, 2.8% either way is significant. From the advantage the Cubs had in their early years to the disadvantage they have now, that's a 9-win swing in a 162-game season. Even compared to average, that's saying that in a typical season, Wrigley Field or day baseball or whatever it is could cost the Cubs 4-5 wins. If this isn't all just a load of crap, that is. But I don't think it is.


Spill it.

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