Wednesday, 22 April 2015

Should live soccer bettors react following an attacking substitution?

As a live soccer bettor how do you react to an attacking substitution? This article examines the impact attacking subs have on soccer to determine if they improve a teams chances of winning.

Substitutions are the most obvious way a manager can try and influence the outcome of a match once it's underway.

A contribution, such as scoring a goal, highlights the impact made by a sub and so called “super subs” emerge into the limelight.

But are these players generally more likely to score than their counterparts who started the game? Answering this could be vital for soccer betting.

The advantages of being a sub
Attacking substitutes do have some advantages over their colleagues who have played from the first whistle:
  • They are fresher.
  • Enter the game when more goals are likely to be scored.
  • As fatigue sets in more space is available.
  • A teams intent can become more attacking.
A sub that plays from the 70th minute will play for 26% of the game, but during a period whereby 33% of goals are scored.

Compare this to a starting player, where only 22% of goals are typically scored during his initial 26% of playing time.

Substitutions occur for a number of reasons. Injuries and red cards force the manager’s hand to make unscheduled changes. However, the most common reason is to replace tired or ineffectual players.

The data below shows that 80% of substitutions happen after the hour mark, while we can assume that virtually all of the alterations made before the interval are enforced ones.

Time of Substitution
% Frequency
0-10
0.4
0-20
1
21-30
1.3
31-40
1.8
41-50
8.1
51-60
7.6
61-70
22.2
71-80
30.3
81-Fulltime
27.4

Substitute patterns
As the table below showcases there is a conservative tendency shown in the type of substitutions that are made.

The most common involves replacing a midfielder with another midfielder. This is twice as likely as the next most common switch where strikers are exchanged, followed closely by replacing defenders, like for like.

40% of the switches do involve a potential tactical readjustment. These can be broken down into attacking changes seen in the table.

Subbed off
Subbed on
% Frequency
Defender
Defender
12
Defender
Midfielder
5
Defender
Striker
2
Midfielder
Defender
5
Midfielder
Midfielder
33
Midfielder
Striker
18
Striker
Defender
1
Striker
Midfielder
9
Striker
Striker
15

Substitutions where there is a potential to alter the priority of a side’s immediate aims are almost twice as likely to comprise attacking players replacing their defensive colleagues.

We can assume that such tactical changes are made with the intention of scoring more goals, although the opposition are obviously able to make adjustments of their own to counter this threat.

And in addition, a side that applies more of their resources to their attack may also be vulnerable to conceding more goals if they over commit in their opponent’s half of the pitch.

This highlights the conflicting interactions that comprise a soccer match and while it's difficult to isolate the effect of a single change, we can look at the general course of events that follow such attacking changes.

Do attacking subs make an impact?
Each team will have a differing level of player ability on the bench. Therefore if attacking substitutions do prove beneficial, we would expect to see it most evident in games with a greater disparity in team strength.

During the 2011/12 season the big four sides - Arsenal, Chelsea, Man United and Man City - increased their attacking capabilities in 40 matches against teams from the mid to lower half of the table:
  • On average the changes began in the 69th minute, and were in play for 26 minutes.
  • Nearly 3/4 of the changes saw a midfielder replaced by a designated striker.
  • Fewer than 50% of the changes resulted in a goal, 24 goals from the 40 games.
  • Opponents scored a goal in 27.5% of those 40 games.
  • The side that made the attacking change scored more goals in 35% of games
Initially the data suggests that attacking substitutions may reap rewards. However, we can easily calculate how well these sides would have expected to do in the latter stages if we use the bookies' pre game expectations for each team, corrected for time remaining and the altered goal scoring environment.

Note these calculations are unaware of the specifics behind a substitute, but from the data collected the results based on pre-game expectations - Pinnacle Sports' odds - are extremely close to the results achieved.

For example, if we model the periods of the 40 games when attacking subs were used, using suitably reduced pre-game expectations, we’d expect 25 goals to be scored and 11 allowed. The actual figures were 24 scored and 11 conceded.

Therefore according to the data the impact of a single attacking player makes little difference to the expected outcomes for the best sides in the closing stages of a game.

Goals flow for better teams simply because they are superior and scoring rates increase with time.

What this means for live soccer bettors
The relative abilities of each side should account for the bulk of a live soccer bettor's decision-making process.

On average, attacking substitutions appear to have little or no effect on a side’s prospects in the final 20 or so minutes, over and above what might normally have been expected to occur in relation to the odds.

Consequently if you upgrade a team's chances following an attacking substitution when betting live on soccer, it would generally be an overreaction.