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Impact of Santi Cazorla

Santi Cazorla moved to Málaga at the beginning of the 2011-12 season. The fortunes of Villarreal nose-dived culminating in relegation. Exactly the opposite happened at Málaga. Relegation candidates in 2010-11, Málaga finished fourth in 2011-12, qualifying for the Champions League for the first time in the history of the club. Cazorla moved to Arsenal a few weeks ago. This post attempts to quantify the impact of Santi Cazorla.

Methodology

  • Compare the overall performance of a club with and without Santi using certain Key Performance Indicators (KPIs)
  • T-tests to determine the statistical significance of the differences in the datasets

Data

  • Full match event data of Villarreal in 2009, 2010 and 2011 seasons provided by OptaPro

Assumptions

  • Giuseppe Rossi was out injured for most of 2011-12. His absence is not factored into the analysis.
  • Cazorla has played in multiple midfield positions at Villarreal. This analysis uses aggregate data of the player in 2009, 2010, and 2011.

Analysis

Points, goals and goal difference are the top-level KPIs to measure the success of a football club. I used shots, assists and the performance in the final third as lower level offensive KPIs that have a big impact on the top level KPIs. Since Santi Cazorla is an attacking player, I will only compare the lower level KPIs of the attacking side of the ball.

Top-level KPIs

  • Villarreal 2010-11 vs. Villarreal 2011-12
KPI With Cazorla 2010-11 Without Cazorla 2011-12 Delta Statistically Significant
Total # of games 37 38    
Points per game 1.59 1.08 -32.34% Yes
Goals per game 1.35 1.03 -24.05% Yes
Goal difference per game +0.16 -0.38 -333% Yes

 

  • Villarreal with Cazorla & without Cazorla in 2009-10
KPI With Cazorla Without Cazorla Delta Statistically Significant
Total # of games 24 14
Points per game 1.50 1.43 -4.76% Yes
Goals per game 1.54 1.50 -2.70% No
Goal difference per game 0 +0.07 - No

 

Observations:

  • Points per game are down in 2009 (with vs. w/o Cazorla).
  • The deltas in Goals per game and GD per game are not statistically significant.
  • Points per game, goals per game and GD per game are drastically down in 2011 compared to 2010. As stated earlier the absence of Giuseppe Rossi for most of 2011 could also have contributed to this huge difference.

Low level KPIs

The low level KPIs look at the impact of Santi Cazorla in the “offensive high-value” zones – the final third and the 18-yard box.

  • Villarreal 2010-11 vs. Villarreal 2011-12
KPI With Cazorla  10-11 Without Cazorla 11-12 Delta Statistically Significant
Shots on Target/game

5.4

4.6

-14.81%

Yes

Total shots/game

13.9

12

-13.67%

No

Penetration into the area(passes completed into the 18y box)

47.77%

44.35%

-7.16%

No

Pass completion % in final 3rd

72.76%

69.59%

-4.35%

Yes

Successful dribbles/game in final 3rd

4.62

3.50

-24.27%

Yes

Dribbles success% in final 3rd

34.41%

27.94%

-18.79%

Yes

ball recovery/game in the final 3rd

2.32

2.42

+4.16%

No

Interceptions/game in the final 3rd

2.32

3.05

+31.33%

No

 

  • Villarreal with Cazorla & without Cazorla in 2009-10
KPI With Cazorla Without Cazorla Delta Statistically Significant
Shots on Target/game

6.25

4.78

-23.52%

No

Total shots/game

12.33

12.78

+3.65%

No

Penetration into the area(passes completed into the 18y box)

42.41%

48.35%

+14.02%

No

Pass completion % in final 3rd

68.07%

66.87%

-1.77%

Yes

Successful dribbles/game in final 3rd

3.54

2.93

-17.27%

No

Dribbles success% in final 3rd

38.12%

40.59%

+6.50%

No

ball recovery/game in the final 3rd

3.13

1.79

-42.86%

Yes

Interceptions/game in the final 3rd

2.13

1.21

-42.86%

Yes

 

Observations

  • Shots on target is down by a significant margin in both datasets
  • Total shots is down in 2011-12 but up slightly in 2009 without Santi Cazorla but  this number is not statistically significant
  • Successful dribbles in the final-third are down in both datasets but the difference is significant only in 2010-11 vs. 2011-12.
  • Penetration into the area (passes completed in the 18-yard box) is down by 7.16% 2011 vs. 2010. However it up by 12.31% in 2009 when Santi Cazorla was not in the line-up.  However, these numbers are not statistically significant. More data is needed to establish the trend
  • The heat map of Cazorla in 2009 vs. 2010 (below) explains this. Santi Cazorla featured a lot on the left wing as compared to a more advanced and central role in 2010.

More observations on the Santi 2009 vs. 2010 heat map comparison

  • Santi Cazorla played more centrally and closer to the penalty area in 2010 compared to 2009
  • Cazorla has a strong influence in the final as well as the middle third of the pitch. This highlights his versatility at playing almost any position across the midfield as well as his contributions to the defensive side of the game.

Shots on Target

  • Villarreal 2010-11 vs. Villarreal 2011-12

Green – 18-yard box; Black – halfway line; Brown – final third (attacking)

Observations

  • Most shots on target coming through the center in both the years.
  • Difference erosion plot shows that there the median location of the shots on targets moves towards the center from left (inside 18-yard box) and backwards (away from the opponent’s goal)
    • This indicates lesser penetration into the 18-yard area.
    • The chances of scoring increase as the shot distance decreases. Here the median shot distance has increased, indicating a reduction in conversion of shots on target into goals.

  • Villarreal with Cazorla & without Cazorla in 2009-10 - Shots on Target Difference erosion plot

 

Observations

  • The median of the location of the shots on target has moved from inside the 18-yard box and the center to outside the penalty box and the left – This is a proxy for the lack of penetration into the final third.

Balance in attack

I looked at the percentage of completions from each zone (right, center & left) of the final third.

 

Note that the size of the center is almost double the size of either left or right zone. The 18-yard box is a part of the center zone.

  • Villarreal 2010-11 vs. Villarreal 2011-12

 

Successful completed passes proportionin the final third

With Santi

2010

Without Santi

2011

Statistically Significant

% thru the left

26.81%

31.84%

No

% thru the center

46.58%

37.08%

Yes

% thru the right

26.61%

31.07%

Yes

 

  • Villarreal with Cazorla & without Cazorla in 2009-10
Successful completed passes proportionin the final third

With Santi

2009

Without Santi

2009

Statistically Significant

% thru the left

27.82%

27.77%

Yes

% thru the center

43.09%

48.65%

No

% thru the right

29.09%

23.59%

No

 

Observations

  • In 2010-11, the completions in the final third are roughly split in 1:2:1 ratio for left, center and right respectively. This is very close to the actual ratios of the surface area in each of these zones
  • However, in 2011-12 (in the absence of Cazorla) the ratio is close to 1:1.2:1 that indicates the attack through the middle suffered.
  • In the 2009 season, the team seem to have had slightly more balanced attack without Cazorla in the line-up

Overall Findings – (aka, what Arsenal fans can expect from Santi Cazorla)

  • Santi Cazorla had a positive impact on all of the top-level KPIs. He also had a positive impact on almost all of the low level KPIs on the offensive side of the ball
  • Santi Cazorla had a positive on the penetration into the 18-yard box
  • The median distance of the shot on target was lesser with Santi Cazorla in the line-up : More penetration = more close range shots on target
  • Cazorla had a positive impact on the overall balance of the attack
  • Cazorla’s heat map of 2010v2011 shows that he has strong influence on the final third as well as the middle third of the pitch. This indicates his versatility to play at multiple positions in the midfield and his commitment to defensive duties.

3 comments

  1. João says:

    Hi,

    As a football fan currently meddling with MCFC’s Opta stats, I gotta say this analysis really intrigues me.

    One question though: how do you define what’s statistically significant and what’s not? For instance, why are the Shots on Target/game statistically significant and the Total shots/game not? (in the Villarreal 2010-11 vs. Villarreal 2011-12 section)

  2. [...] Football’s Ravi Ramineni use of statistical analysis on Cazorla’s impact at Villareal and Malaga further supports the notion that the diminutive Spaniard will be an important player for [...]