Learn how cards can affect soccer outcomes

• Posted by: csabax
• 08 April 2013
• Football
• Comment!

A red card is one of the most significant events that can impact the outcome of a soccer game. This article examines the importance of bookings (both red and yellow), how they affect game probabilities, how managers adjust and why they place away teams at a disadvantage.

The red card: a soccer game changer

 

While everyone understands the circumstantial effect of red cards – the immediate loss of a player – statistical analysis helps us better understand the extent to which teams are negatively impacted when they receive a red card.

 

Unsurprisingly, the team that had a player sent off gained fewer points per game. Over the 60 Premier League games where a team saw a red card in 2012, 20% dropped points at the final whistle when compared to their predicted points (based on the score prior to sending off).

 

For the 20 teams that were drawing at the time of receiving a red card in last seasons Premier League, 65% went on to lose, 30% held on for a draw and just 5% – one team – managed to win.

 

The negative impact of a red card on a team is also evident in the amount of goals they score and concede. A study by Titman et al. (2012) highlighted that teams playing against a red-carded rival benefited by a 64.5% scoring rate increase.

 

Previous research looking at a number of Premier League seasons also indicates that the longer teams have a player deficit, the worse off they will be. If a team receives a red card in the first minute, their average goal difference in the game would be reduced by about 1.5 goals. This is reduced to 0.85 and 0.62 if a team is effected by a red card at half-time and 60 minutes respectively.

 

These figures can enable live bettors to gauge whether live odds have accurately changed to reflect red card incidents, and potentially to measure the significance of yellow cards, the most common precursor to a red.

 

Don’t underestimate the importance of yellow cards

 

With the knowledge that red cards can dramatically change the expected course of a match, and given a yellow card can lead to a red, bettors should understand the importance of a yellow card as more than a pause in play.

 

Referees have a tendency to ‘even up’ decisions

As yellow cards increase during a game, the in-play probability of a player being dismissed grows. Titman et al. (2012) stated a yellow card to any player on a team in the Premier League more than doubles the hazard of a straight red card to any other player on that team.

 

Interestingly, Titman also discovered that a team’s booking rate increases by 25% if the opposing team receives a yellow card, which reinforces the notion that referees have a tendency to ‘even up’ decisions during the game.

 

How cards impact on a manager’s tactics

 

When a team loses a player to a red card, the manager must react to the situation and change his tactics accordingly. Like a manager, a bettor should judge how important the player sent off is to the team, how the card impacts the shape of the team, what can be done to mitigate the situation and what bearing the sending off will have on the opposition.

 

A perfect example of how a red card affects the game can be seen when analyzing the recent last 16 Champions League second-leg game between Manchester United and Real Madrid.

 

The Reds were controlling the game – United nullified Madrid’s potent attack by using Danny Welbeck to restrict Madrid’s most creative player Xabi Alonso – after Sergio Ramos had scored an own goal to give Alex Ferguson’s team a 2-1 aggregate lead.

 

However, the game turned when United winger Nani was sent off for a dangerous challenge on 56 minutes. Not only did United have a man less, but they also had to move Welbeck to left midfield, in order to preserve their second bank of four – allowing Alonso to roam free and become more creative.

 

Known for reacting to situations quickly, it took Madrid’s manager Jose Mourinho just four minutes to make a substitution – replacing Alvaro Arbeloa with Luka Modric, and swapping Sami Khedira to right back.

 

Red cards dramatically change the match

The change turned the game as Modric controlled the centre of midfield with intricate passing sequences, and scored the equaliser with a long-range strike. After equalising, Real were in the ascendency and retained the ball superbly, scoring their second goal within 13 minutes of Nani’s red card.

 

Ferguson had the better of Mourinho when it was 11 vs. 11, however the red card changed the game and after the sending off Mourinho reacted both immediately and intelligently.

 

Are away teams at a disadvantage?

 

It is known that teams playing at home perform better than away – read about Home Field Advantage here – but how much help do they get from the referee?

 

Studies highlight that the probability of receiving a red card is different between home and away teams. Data collected from the Champions League from 2002-2007 showed that in only 24.3% of games did the home team incur more yellow cards than the away team.

 

Away teams collected 84% more red cards

In that period home teams received a red card in 6.42% of games, while the away teams received them in 11.82% of games. This means that away teams picked up red cards 84% more often than home sides. Interestingly, in 82.89% of games there were no red cards.

 

Research on the Bundesliga (Anders & Rotthoff) from 2004 to 2009 highlighted that the effect of cards on the home team is different to that of the away side.

 

Titman et al. (2012) found that a home red card increases an away teams’ scoring rate by 60% and decreases the home sides’ scoring rate by 17%.

 

In comparison, a red card for the away team sees the home team’s chances of scoring increase by 69% and the away team’s chances decrease by a massive 42%, which shows the handicap for away teams is more severe.

 

Final thoughts

 

This article contradicts the repeated soccer cliché that playing against ten men is more difficult than eleven. Unlike a goal, a red card merely presents an opportunity and a challenge to the respective teams.

 

Over many games a team will benefit from facing a team with fewer players, but in a one-off game the team need to exploit their advantage, which may require a different tactical approach. Basically, a red card is a potential game changer, but the game still has to change.

 

The data on the impact of red cards to goal probability should be of special interest to live soccer bettors, as this can be used in conjunction with subject analysis of specific game dynamics to help gain in-play advantage.

 

With the knowledge that referees tend to favour home teams when disciplining players, it is important to look at influences on the referee. Because of inconsistencies across individual referees’ tendency for cards, profiling referees is important, however this is more than likely accounted for in the bookmaker’s prices, so investigating influences on the referee themselves could be profitable – this will be discussed in a future edition of The Pulse.

 

Click here for the latest Champions League odds online.

 

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