* What fans influence: subconscious referee biases (not wanting to be booed for a close call), heckling that slightly impacts players’ focus, objects being waved in their line of sight, noise levels rising at inopportune times, etc.
* Travel/comfort: the home team players sleep in their own custom-tailored sleeping environments (these can include stuff like oxygen tents, not just nice mattresses), don’t spend time encased in a plane / train / bus environment not designed for optimizing future athletic performance, and don’t have travel stresses and logistical headaches. Also for those inclined, the local club / strip club / groupie scene doesn’t hold the same mysterious allure on a random Tuesday night as it might for the lad from out of town.
The second set of factors remains even when fans aren’t allowed inside the arena.
It would be interesting to control for distance travelled, and see if a third factor emerges where teams play worse even if they can stay at home and don't have a significant train/plane/bus journey to make. The third factor could be very minor differences between the grounds, or a pure placebo effect, or a tactical reaction to the placebo effect (teams often set up more conservatively away from home because they expect to be at a disadvantage).
(I haven't read the article yet - I've used up all my free Economist articles - so maybe it touches on this, but it's neglected in your post).
I've seen results before from American sports saying travelling East is worse for a team than travelling West, because of jetlag effects, and travelling to Colorado is bad, because of altitude effects. Those results would be tricky to tease out with your approach: if West Coast teams consistently perform 5% worse when playing on the East Coast, you can't tell that apart from East Coast teams playing 5% worse on the West coast by looking solely at win rates. The study I'm thinking of did something clever with looking at multi-game series to evaluate the jetlag effect.
Teams who were on the boundaries of these often took advantage of it, my home team played in a larger than average pitch and you would clearly see teams that went in full pressure to lose a lot of gas by the second half, the best coaches knew how to make this count. On the other side of the spectrum, teams with shorter fields favoured playing long balls straight from goal kicks to the strikers.
Tbf I miss a little bit the days where these small inconsistencies would affect the game and require a little bit more studying on the coaches part.
However, the really interesting thing was I remember hearing an interview with an Arsenal player (possibly Lee Dixon) saying he knew just how to hit a soft pass into a shallow groove that ran along the side of the pitch - it looked like the ball was going to go out of play but it would catch this groove and move up the pitch instead.
The home fans were also much more in their faces (though it never helped seemingly when we fell off a cliff at the 80 minute mark to throw it all away...)
Maybe the difference is minimal and melts away after the first ~15 minutes when you get into the game, but you can yourself into quite a big hole in the first 15 minutes (https://www.youtube.com/watch?v=KRx3KrQ83mc)
Went to one. Was way Wilder than a typical hockey game
Also pitch sizes are not strict and both width/length vary.
The comment doesn't cover the article contents.
However, structural advantages do exist. The best example is actually MLB, where each team's field is shaped differently. The dimensions of the park impact hitters to an extent that it makes sense to tailor the roster composition to the yard at the margins: lefty hitters who loft many short flyballs in Yankee Stadium will hit homers that would be easy outs in most places, the typical left fielder won't be able to cover enough ground defensively in Pittsburgh, etc.
Many years ago, fans were allowed in the outfield at baseball games and were held back by a rope. A home run was when the ball flew (or rolled) past the rope.
Since the "line" was just a flexible rope, when the home team was batting the crowd would push the rope forward to help raise the odds of there being a home run. When the away team was batting, they would pull the rope back to lessen the odds.
Also, reminds me of the old Gatorade commercials with Old Shaq were he talks about how basketball changed (in the future) and he says "And then they put in the moving backboard..."
With the caveat that this is for baseball and not football, home field advantage has shrunk tremendously over the years. Just look at the curve of "field kindness" over the history of the MLB, it is insane how much of a difference the field you were visiting used to make!
(my favorite bit is the curve ball when it comes to fields that confer a statistical advantage to the visiting team!)
Park dimensions + team makeup is a combination that can contribute heavily to home team advantage. The short porches in Yankee Stadium (especially in right) have traditionally granted an advantage to the Yankees' often left handed sluggers. The more the field dimensions vary from the norm, the more the home team has an advantage to tailor their team makeup to exploit them. Parks with high walls, short porches, heavy prevailing winds, deep outfield fences, or absurd dimensions ( Think Willie Mays fielding center at the Polo Grounds) all present opportunities for exploitation.
While the Astros had more wins on the road than at home during the regular season from 2017-2019, their 2017 postseason home/away batting splits were wildly inconsistent. Boston had the best home record in MLB by six games during the 2018 season in which they were found to be relaying signals to batters. I'd suggest that home field presents a greater opportunity for outright cheating as well.
Do you think it has to do with roster building? Like the Rockies don't spend money on pitching because pitching has less value at Coors, so they load up on offensive talent instead?
While other teams play a single (or handful of) series a year at Coors Field, the Rockies have to adjust to breaking pitches being more effective while playing away half the time which would be a bigger disadvantage than the ball not flying as far at away ballparks.
I would've thought stuff like being used to the visual backdrop behind a pitcher's arm would let you see a pitch better or knowing where to stand to best play a ball caroming off the outfield wall would give more of an advantage.
And given that, relative to the other sports, there's an actual difference in the rules and play of the game based on which team is at home (less so now hat the DH is in both leagues).
There are times of little action where the ref separates fighters, typically as the inaction goes on the crowd boos more and more. With no crowd different strategies have been implemented to allow for a slower pace at times.
Also the commentators talk so loud in the empty arenas the players have said they can hear them and make adjustments based on their commentary.
Last week a commentator shouted out to stop a fight at a UFC event which has caused some turmoil afterwards as well.
Fans can also now hear all the strikes and slams to the mat watching at home because of the silence. It's made it a much better experience imo.
While all this is happening the judges are also sitting ring side so there is certainly a human factor of outside influence going on in their decision making. (MMA and boxing judges are notorious incompetent)
This above result could easily take place in VR for the opponents facilities and arena. Model their locker rooms, field/court/etc, model screaming fans of the wrong color, model boos, etc etc. Essentially try and eliminate some home field advantage by making it feel more like home.
I'd be surprised if gridiron teams don't do something similar since crowd noise is genuinely a tactical issue there (it's more disruptive to the offense) in addition to a psychological one.
Also a lot less flopping on the ground in fake agony. With no crowd to play to, players fall over and then get back up again. It's very refreshing to watch.
For some (and I mean in no uncertain terms, for black players and those from other minorities), it's probably a godsend, and that sense of 'relief' probably does have a measurable outcome (i.e. some players raising their standards, and others doing likewise to follow them).
OPTA and their like measure a lot of data points. So this hypothesis could probably be proved. Passing percentages, XG and assist rates for example, but I'd reckon individual running distances will be a particularly interesting metric to explore.
Any of those stats could go up or down for all players, but I do suspect there will be observable changes, because of these new playing conditions.
It's very easy to trip when sprinting at full speed while concentrating on a single object. The slightest external force will put you on the ground very quickly.
Rugby, Gridiron and Ice Hockey players will also know that, but frequent falls under pressure are expected by the rules. In soccer, it's a lot more subtle (shirt pulling, various rules around obstruction, the height at which you keep your hands... all sorts). There's plenty of opportunity fool a referee, so you will instinctively try to do so. Especially if your style of play generally draws opposing players into fouling you regularly already.
I'd say that the introduction of video referees (VAR) are probably more effective in stopping that kind of behaviour, than empty stadiums. But you'd never know.
Jurgen Klopp was always trying to get the crowd engaged and pumped up because he believes it has a huge effect on how his Liverpool team play. Without the crowd they seem to be missing that extra 1% of intensity that made them incredible pre-lockdown.
Whereas Manchester City probably don't feed off the crowd as much as Liverpool do. Manchester City are all about rehearsed routines so they may even find it easier without a crowd as they'll be able to communicate much easier.
I don't know whether this study measures only the outcome or contributing factors. For example, in Germany, anti-COVID measurements lead to the following result: way fewer to now discussions with the umpire. Pack forming has been forbidden. Empty stadiums are only part of the measures but, in my opinion, not the contributing factors.
These factors contributed massively to the pace of the game. And if no players are trying to influence the umpire - well, you get different results.