Premier League season has had a wild start: How to explain rise of goals and penalties?

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The 2020-21 Premier League season has been in full swing for just over a month, and it's already promising to be the most entertaining and unpredictable in the history of the competition.

Going into the weekend's games, Everton and Aston Villa are the surprise pacesetters, with the early-season slip-ups by Liverpool and Manchester City suggesting that the favourites will not break so far from the pack this time around.

Instead, it's been about more than unexpected leaders and shock results. It's also been a story of wildly fluctuating statistics in terms of goals scored, clean sheets, penalties awarded and the drop in the value of home advantage.

This season has been off the scale in terms of numbers, so we've taken a deep dive into the data in a bid to work out why the Premier League has gone crazy.

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Goals are flying in

This season has already seen plenty of remarkable scorelines, such as Liverpool's 7-2 defeat at Aston Villa and Manchester United's 6-1 loss against Tottenham at Old Trafford.

Marcelo Bielsa's Leeds, promoted as winners of the EFL Championship last season, added to the craziness by opening their campaign with successive seven-goal thrillers -- Leeds lost 4-3 at Liverpool in their first game before bouncing back with a 4-3 win against Fulham at Elland Road.

The average goals-per-game ratio stands at 3.58, which is way higher than the Premier League record of 2.82 goals-per-game, a mark set in the 2018-19 season.

Throughout the all-time history of English football, which dates back to the inaugural season in 1888-89, there have only ever been 18 top-flight campaigns with an average of at least 3.58. The highest ever was 4.63 in 1888-89. Of those 18 seasons, only 11 came after 1900 and the most recent was 1960-61, with 3.73.

This season is proving to be an outlier in Premier League terms, with the past five seasons (listed with 2019-20 first), ending with goals-per-game averages of 2.72, 2.82, 2.68, 2.80 and 2.70, respectively.

Clean sheet bonus in short supply

There have been 48 Premier League games so far this season and the first 0-0 was not recorded until game 47, a forgettable stalemate between West Brom and Burnley at The Hawthorns. Beyond that, there have been only 22 clean sheets in 48 games; at the current rate, that adds up to 174 shutouts over an entire Premier League season of 380 games.

While the goals-scored ratio has veered dramatically off course in an upward trajectory, the clean-sheet ratio has plunged downward and is heading for a much lower number than usual.

Over the past two seasons, there have been 207 clean sheets overall in the Premier League. In 2017-18, that number climbed to 226, and it was 214 in 2016-17 and 215 in 2015-16.

Aston Villa keeper Emiliano Martinez has three clean sheets in four games so far for Dean Smith's team, while Rui Patricio at Wolves has racked up three in five in the race for the Golden Glove.

Penalty awards have rocketed

The head of Premier League referees, Mike Riley, warned ahead of the 2020-21 season that fans should expect a dramatic rise in the number of penalties being awarded due to the introduction of a much more stringent interpretation of handball, and he has been proved correct.

So far this season, a remarkable 29 penalties have been awarded by match referees or VAR officials and 25 have been scored.

With Premier League officials also told to award a retake if a goalkeeper has encroached off his line when saving, it has become much harder for keepers to keep them out. Manchester United's David de Gea was the first to fall foul of the rule, with his save from Crystal Palace's Jordan Ayew deemed illegal before Wilfried Zaha netted from the retaken penalty.

"I think it was a little unfair," de Gea said at the time. "I was only a tiny bit forward, but hey, that's the rule. But I don't get why they're allowed to change the player that takes it. It takes the pressure away from the player who missed the first time."

After five rounds of games last season, only 13 penalties had been awarded in the Premier League, with 11 being scored. The most recent high point, after five match days, came in 2016-17 when 20 penalties were awarded and 15 scored.

Home advantage has been lost

One of the biggest impacts of teams playing in front of empty stadiums, due to the restrictions imposed as a result of the coronavirus pandemic, has been the diminishing value of home advantage. So far this season, the away win ratio stands at 46%, which is considerably higher than the previous record figure of 33.7% in 2018-19. And that was the highest-ever recorded ratio for top-flight away wins in league football.

Throughout the history of the Premier League, dating back to the first season in 1992-93, the all-time ratio of away wins is just 28%. The lowest ratio of away wins in a season came in 2010-11, when only 24% of matches were victories by the visiting team. At the current rate, the 2020-21 season is on course to see twice as many away wins as in 2010-11.

Jimmy Floyd Hasselbaink, the former Leeds and Chelsea forward, believes that the lack of fans inside a stadium is impacting home teams, while also contributing to the spike in goals and away wins.

"I think that the crowd not being there [is having an effect] for instance on midfielders," Hasselbaink told Sky Sports Monday Night Football. "When they are beginning pressured or pressed, you normally have the crowd shouting, especially when playing at home, and these things are not there at the moment, so concentration is different. It is totally different."

So what is going on?

Within the game, there is a distinct lack of certainty about why this season has been so unpredictable. Coaches and players are clearly still attempting to work out the reasons behind what has become something of a free-for-all.

The absence of fans inside the stadiums is an obvious issue that is impacting both teams. The home side have lost the ability to make their own patch a fortress, with stadiums like Anfield, Elland Road and Selhurst Park devoid of their usually passionate atmosphere. Without the noise, the home side's players maybe drop their level by a slight percentage and that is enough to blunt their edge. This helps the away team, who can play without the pressure of the home support and execute a tactical game plan worked out on the training ground.

The loss of outside influences has also made life easier for officials, who may now be awarding more penalties because they are less concerned about the backlash from angry and noisy supporters inside the ground.

Fitness is perhaps another factor. The lack of a proper preseason has left all teams without their usual conditioning programme, so if fatigue is an issue, it will show in the form of mistakes being made due to tiredness affecting concentration levels.

In truth, nobody knows the root cause of the issues at play this season. Time will perhaps tell on that, and the season may also level out and return to some kind of normality once the coaches get to work on defensive flaws. But in the meantime, nobody is complaining about the levels of entertainment and excitement.