Development of a software system which identifies the counter-pressing behavior of the team. The development of the system was motivated by a need for more ambitious used of player movement data that is now widely available in the sport.

1. Testing and evaluation of a software system to recognize
the behavior of the teams under counter pressing in
soccer using the player tracking data
Introduction
The following reports discuss the process of development of a software system which identifies
the counter pressing behavior of the team. The development of the system was motivated by a
need for more ambitious used of player movement data that is now widely available in the sport.
These data have been largely used to produce distance, speed and acceleration measures (Di
Salvo et al., 2009; Gregson et al., 2011) as well as abstract mathematical forms that may not be
understandable to coaches and players (Fonseca at al., 2013). The report describes how system
requirements were analyzed before the system was specified. The system structure was
designed before an evolutionary development approach was used to implement components,
testing definitions of tactical events in an exploratory and refining system requirements if
necessary. The system was evaluated by comparing the counter pressing events that were
automatically identified with those recognized by detailed human video analysis. This report
commences by describing the pressing in soccer before discussing the system requirements
and the feasibility of developing the system. The second section is the system specification
which provides an objective definition of counter pressing in soccer as well as identifying the
main inputs and outputs of the system. The third section describes the design of the system
and then the final section explains how the system was tested and evaluated showing the
evaluation results.
Counter Pressing in Soccer
Counter pressing is the strategy of winning the ball back as soon as it is lost in the opposite
half. This is an effective tactic because the player who has just won the ball is vulnerable, as he
may be still getting the ball under control. Also, He does not get enough time to fully scan the
distribution of his teammates and opponents. It is based highly on the speed and organization
of the opposite team players who are looking to pressure the man with the ball. The idea is to
regain possession quickly as high up the pitch as possible, thus countering the counter-attack.
Technically it is described as when the player A gets the ball in his own half from the opposite
team and then the opposite team tries to close in the with high intensity to stop the
counter-attack. In order to pass the ball quickly in the forwarding direction, Player A then passes
the ball. These shot can be long-range shot or short-range shot depending upon the tactical
strategy of the team and organization of players

2.
Fig 1. Showing the counter pressing behavior of both teams. a) Ball in the left half of Team A b) Possession
change happen in the half of team A. c) Team B starts pressing the player with the ball. d) showing the
option to pass the ball
Requirements Analysis
Viewpoint analysis allows system requirements to be considered from multiple perspectives
(Finklestein and Fuks, 1989). The main viewpoints the challenge identification system were:
Soccer tactics
Coaching and feedback
Software and hardware constraints
Software engineering
Typically, viewpoints are represented by stakeholders or viewpoint authorities which can lead to
conflicting requirements and the need to resolve such conflicts. This involves viewpoints being
structured into a hierarchy so that there is a mechanism for conflicts from lower level
viewpoints to be resolved by arbitration. During the current exercise, there was no specific
customer group and so all of the viewpoints were represented by the software developer which
minimised the number of conflicting requirements that were generated. The viewpoint of
coaching and feedback considered how the system might be used by performance analysts,

3. coaches and players to learn about challenging tactics they are implementing, how effectively
they defend when opponents use challenge tactics and to consider the challenge tactics of
future opponents.
The requirements derived from this viewpoint included identifying players involved in counter
pressing events, an ability to display graphical portrayals of pressing and a means of identifying
video sequences of presses.
The main software constraint was that the system had to be developed in Matlab 7.0.1 (The
MathWorks Inc., Natick, MA) using the standard libraries available at Cardiff Metropolitan
University.
This also led to a hardware constraint which was that the system had to be implemented in the
performance analysis laboratory of the university. A further software constraint was the data
files provided for the match used to test the system.
The player trajectories were provided by Prozone Sports (Leeds, UK) while supplementary files
containing chronologically listed event and possession records were provided by the module
co-ordinator of the Software Engineering module.
The match video was also provided meaning further data files could be created if necessary, but
it was desirable that the system could run with the data files provided. From a software
engineering perspective, the system needed a good response time, especially during the
evolutionary development process that would be adopted. If the system processed data slowly,
it could delay time to market as the time between successive versions being implemented and
tested would be longer than necessary.
Reusability was a further requirement that came from the software engineering viewpoint.
Tactical analysis systems could be implemented for a variety of different tactical events. Future
work of this type could be much more efficient if useful system components of common benefit
to multiple analyses were separated from pressing specific components allowing them to be
used elsewhere.
System Specification
Prozone has provided X and Y coordinates of all the players for each tenth of a second. The
center of the circle is taken as (0,0). The positive X goes from left to right and the positive Y
goes from top to bottom. There are total 54000 rows for whole 90 minutes.
The other file is an event file has seven columns which store a record for each instantaneous
event performed during the match.
The 7 column of event files are
1. Half (1 or 2)
2. Mins (on video)
3. Seconds (on video)
4. Team (1 = Hull, 2 = Cardiff)
5. Player (1 to 26, 1 to 12 are the Hull players, 13 to 26 are the Cardiff players, 0 = N/A)
6. Event (1 = Pass, 2 = Receive, 3 = Touch, 4 = Shot, 5 = Corner, 6 = Throw In, 0 = N/A)
7. Outcome (1 = Retained, 2 = Lost, 0 = N/A).

4. Another event that is used in the system is the dribble event. Though it is not included in the
eventfile list, it is calculated as if a player receives the ball and then the next event for the same
player is pass or shot, then we can consider that the player was dribbling the ball.
The main output file has the distance for three instances :
1. Half
2. Team with the ball
3. t0 = time when the player receives the ball
4. t1 = t1 - 1 sec
5. t2 = time when the ball is passed by the same player
6. t3 = Pass received by the player
7. Index of the last pass received by the player
8. Player passing the last pass
9. The player receiving the last pass
10. Length of the pass
11. Type of the pass
The counter pressing is analysed over a period of time. There are 3 times involve
here.
First is t1 when the possession is changed in the same half, t0 is taken to check the position 1
sec before the t1, So, t0 = t1-1sec and finally, the t2 is when the dribble is ended. There is one
more time t3 which is the time when the player receives the passed ball. This is time is
important in the calculation of the distance of the pass. The path of the player who is pressing
and the player with the ball is shown from t1 to t3. An arrow will be drawn to show the length of
the pass
Before going farther in the implementation stage, let us specify the conditions for
counter pressing events. Pressing is defined when the distance between the player
who is about to receive the ball and after receiving should decrease rapidly. Counter
pressing is when the above event happened in the same half of the team who has just
now received the ball. There are 4 criteria that define the counter pressing is as
follows :
1. The first criteria is the change of possession of the ball. The possession
change should happen in the same of the half the team receiving the ball
2. The type of event is a successful pass received.
3. The player receives the ball then should dribble to pass
4. There should be players of an opposite team player in the range of 12.4m of
the player who has received the ball
5. The distance between them should decrease to show pressing
6. Final pass is successfully received.

5.
Fig 2. System inputs and outputs
System design.
Architectural Design
The first file which is the “Main_file.m” is the collection of all another file. This is done so that
each file can be run individually to check the functioning of each one
1. Setting up variables: ​When the main file is executed it initialize the 4 files. The first file
that is executed is an initialized file which set up the variables like the goal width, the
penalty and six yards box.
2. Setting up Pitch: ​The second one files set up the pitch length and width. This also loads
the data for X, Y, and the eventfile.
3. Analyzing Counter Pressing:​ There are X steps involves in this. The first of them is
a. Determine possession change in same half: A for loop is run through each row of
eventfile. IF statement is used to check the criteria of changing the ball
possession. There are 4 different cases as for each half of the game and the
team. The additional conditions of half of the game and the coordinates of the
player were put to identify those changes happening in the own half of the team.
The player who receives the ball is P1.

6. b. Determine the nearest player: ​Opposite team’s player found out in the range of
12.4m from P1. 12.4m is defined as the product of High speed(reference) and
the time for pressing. High speed is taken as 5m/s and time pressing is taken as
2.4sec(reference). This is done for 3-time instances and they are kept in a new
file to analyze as if the distance was decreasing in from t0 to t2.
Fig 3. Image showing the pressing area and movement of the player and the ball
c. Pass length: Finally the length of the pass is found out to determine the approach
of counter-attacking of the team.
Fig 4. Possible passing of the ball
The routine of data files controlling the software. Each file produces a file which is used by
other following algorithms to find new results

7.
Fig 5 Hierarchy of subroutines
Debugging
Debugging was done by different methods. An algorithm was developed to debug
what's happening in the video is matching to the values. Also takes times in mins and
sec and tells about the team, player involved, half, type of event and the coordinates
of the player involved.
Other than this, temporary variables were used and sometimes the conditional
statement. The output of each iteration was also checked when the result was
looking ambiguous.
Testing and evaluation​.
The system is tested by comparing the 2 different results obtained. The one is
obtained by the software analysis and the other one is obtained by the human
analysis. False-positive and false negative were analyzed to see the efficiency of the
algorithm.
Evaluation of the system was done by watching the video and then comparing it with
the actual results found. There were 313 incidents where possession changes out of
which only 45 were those events happened in the same half of the team gaining the
ball. Out of these 45, there were 26 events where the final player has received the ball
after completing the dribble. There were 8 events which the algorithm said it satisfies

8. the definition but in those 8 when saw it manually it was involving the goalkeeper
hence it is not counted as the counter pressing event.
Software Human Observations
No Yes Total
No 14 5 19
Yes 8 18 26
Total 22 23 45
Table 1. Showing the comparison of the final 45 events which satisfy the criteria.
Draw Pitch
The blue dot has received the ball from the white dot team in their half. Blue dot is tracked at
three given intervals. Finally, the ball is pass to the player of their team shown by the red line
Fig 6. Pitch diagram output
The software can be tailored for use with any accurately recorded player movement
data such as GPS data. The subroutines for determining distances between players,
identifying the nearest opponent, drawing the pitch and initializing event and
movement data structures have been isolated for use with other tactical analysis
systems.

9. Finally, the software system identifies the counter pressing event effectively. There
are some events which are ambigous and can be debated. The human analysis helps
in analyzing it and bringing it to a conclusion. The using for data and software
algorithms helps in identifying the events hence the manager doesn't need to go
through the whole video to find out the pattern of playing of opposite team
.
Bibliography
Di Salvo, V., Gregson, W., Atkinson, G., Tordoff, P. & Drust, B. (2009), Analysis of high
intensity activity in Premier League soccer, ​International Journal of Sports Medicine​,
30, 205-212.
Finklestein, A. and Fuks. S. (1989), Multi-party specification, In ​Proceedings of the 5​th
International Workshop on Software Specification and Design​, Pittsburgh, PA, pp.
185-195.
Fonseca, S., Milho, J., Travassos, B., Araújo, D. and Lopes, A. (2013), Measuring
spatial interaction behavior in team sports using superimposed Voronoi diagrams,
International Journal of Performance Analysis in Sport​, 13(1), 179-189.