# Analyzing FC Barcelona's assists pattern

How to use the eurolig package to analyze the patterns in assists for FC Barcelona in this Euroleague season

## Introduction

eurolig is an R package that I just created for obtaining and analyzing basketball data games from the Euroleague. In this post I show how to use the package to analyze different aspects of the way FC Barcelona passes the ball in this Euroleague 2018-2019. More specifically, we are interested in finding out:

1. What type of shot each assist generates

2. How many points are being generated by each assist

3. Who assists who

4. How to visualize the patterns of assists

## eurolig

The eurolig package is in its initial phase and still has many bugs. At the moment of writing, the package only provides tools to work with play-by-play data, but I hope to add the possibility to work with other types of data shuch as shot location data and regular boxscore stats.

The package can be installed from Github:

# install.packages("devtools")
devtools::install_github("solmos/eurolig")

Note, however, that the package is in its experimental phase and there will be numerous changes as I keep developing it. Having said that, I encourage you to download the package and play around with it. If you detect a bug or think of useful feature, please let me know.

You can keep track of new features and releases in the NEWS.md file from the package repository.

## Analysis

The play-by-play data allow us to answer many questions that cannot be answered with the regular boxscore data. In this case, we will use these type of data to answer the questions of interest that we introduced above.

### Data extraction

We can obtain the play-by-play data by entering the game code (or game codes) toguether with the starting year of the season we want into the extract_pbp() function.

The game code can be found in the URL of the game web page. For instance, the last game that FC Barcelona played in this Euroleague at the moment of writting was against Bayern Munich in the German city. The game URL is

https://www.euroleague.net/main/results/showgame?gamecode=219&seasoncode=E2018

We see that the game code is 219. Entering this code together with the corresponding year in extract_pbp() we obtain the play-by-play data in a tidy data frame:

library(eurolig)
game_pbp <- extract_pbp(game_code = 219, season = 2018)
game_pbp
## # A tibble: 518 x 18
##    game_code play_number team_code player_name play_type time_remaining
##    <fct>           <int> <fct>     <fct>       <fct>     <chr>
##  1 219                 2 <NA>      <NA>        BP        10:00
##  2 219                 3 MUN       RADOSEVIC,… TPOFF     09:59
##  3 219                 4 BAR       TOMIC, ANTE TPOFF     09:59
##  4 219                 5 BAR       RIBAS, PAU  3FGM      09:37
##  5 219                 6 BAR       TOMIC, ANTE AS        09:35
##  6 219                 7 MUN       LUCIC, VLA… 2FGA      09:20
##  7 219                 8 BAR       TOMIC, ANTE D         09:18
##  8 219                10 BAR       PANGOS, KE… 2FGA      08:58
##  9 219                11 MUN       LUCIC, VLA… D         08:55
## 10 219                12 MUN       JOVIC, STE… TO        08:34
## # … with 508 more rows, and 12 more variables: quarter <fct>,
## #   points_home <dbl>, points_away <dbl>, team_name <fct>,
## #   player_id <fct>, player_dorsal <dbl>, play_info <chr>, seconds <dbl>,
## #   home_team <fct>, away_team <fct>, home <lgl>, season <int>

In the present analysis we want to analyze more than just one game. Specifically, we want to obtain all the games FC Barcelona has played in this ongoing Euroleague. Instead of searching around the Euroleague website for all the different game codes, we can just use the function extract_team_pbp(). With this function we just need to enter the three letter team code and the year we want to obtain the data for all the games that the team has played in the given season.

Let’s proceed to download the data of the games that FC Barcelona has played so far (March 25, 2019):

pbp <- extract_team_pbp(team = "BAR", season = 2018)

Note that the process takes a relatively long time to return the final data frame. This in not a bug. The function is designed to be slow. The Euroleague’s API documentation asks to leave a few second between succesive requests.

### Analysis of assists

To answer the diferent questions that we mentioned in the introduction we are going to use the function get_assists(). Entering the play-by-play data into this function we obtain a data frame with detailed information about each assist recorded in these games. This resulting data frame can be used to answer many interesting questions with just few lines of code.

library(dplyr)
assists <- get_assists(pbp, team = "BAR")
assists
## # A tibble: 475 x 12
##    game_code season passer shooter shot_type points time_remaining quarter
##    <fct>     <fct>  <fct>  <fct>   <fct>      <dbl> <chr>          <fct>
##  1 2         2018   HEURT… CLAVER… 2FG            1 09:43          1
##  2 2         2018   CLAVE… TOMIC,… 2FG            2 08:39          1
##  3 2         2018   HEURT… TOMIC,… 2FG            2 07:44          1
##  4 2         2018   HEURT… SINGLE… 2FG            2 07:34          1
##  5 2         2018   CLAVE… SINGLE… 2FG            3 03:19          1
##  6 2         2018   ORIOL… SERAPH… 2FG            2 00:46          1
##  7 2         2018   SERAP… KURIC,… 3FG            3 00:13          1
##  8 2         2018   HEURT… ORIOLA… 2FG            2 07:08          2
##  9 2         2018   HEURT… SERAPH… 2FG            2 04:58          2
## 10 2         2018   BLAZI… PUSTOV… 2FG            2 01:17          2
## # … with 465 more rows, and 4 more variables: seconds <int>, foul <lgl>,
## #   and1 <dbl>, ftm <dbl>

#### What type of shot each player generates when he assists a teamate?

With the assists data frame we can find out what type of shot each assist leads to. An assists can lead to three point shot, a two point shot, a shooting foul (where at aleast one foul shot is made) or an and 1.

In this case, let’s say we are only interested in knowing whether the shot following an assist was a two or a three point shot. The FC Barcelona players with at least 10 assists total have distributed their assists as follows:

assists %>%
group_by(passer) %>%
summarise(
assists = n(),
two_pointers = sum(shot_type == "2FG", na.rm = TRUE),
three_pointers = sum(shot_type == "3FG", na.rm = TRUE),
3pt_ratio = round(three_pointers / assists, 3)
) %>%
arrange(desc(assists)) %>%
filter(assists > 10)
passer assists two_pointers three_pointers 3pt_ratio
HEURTEL, THOMAS 138 101 37 0.268
PANGOS, KEVIN 92 55 36 0.391
TOMIC, ANTE 53 34 19 0.358
RIBAS, PAU 47 33 14 0.298
HANGA, ADAM 30 20 10 0.333
SINGLETON, CHRIS 26 15 11 0.423
CLAVER, VICTOR 23 12 11 0.478
KURIC, KYLE 21 13 8 0.381
ORIOLA, PIERRE 15 8 7 0.467
BLAZIC, JAKA 12 9 3 0.250
SERAPHIN, KEVIN 12 8 4 0.333

In this case, Heurtel has the second lowest ratio of assists to three pointers with respect total assists (0.268). On the other hand, Pangos has a substantially higher proportion of assists that lead to three pointers (0.391).

It’s the big and mobile players, like Claver, Singleton or Oriola, that have the highest proportion of assists going to three pointers.

#### How many points each player’s assists generate?

As we have seen, not all assists are created equal. An assist to a three pointer generates two more points than an assist that results in a shooting foul where the shooter only scores one foul shot.

With the following lines of code we can compute how many points each player’s assists generated:

assists %>%
group_by(passer) %>%
summarise(
assists = n(),
points = sum(points, na.rm = TRUE),
ppa = round(points / assists, 3)
) %>%
arrange(desc(assists)) %>%
filter(assists > 10)
passer assists points ppa
HEURTEL, THOMAS 138 311 2.254
PANGOS, KEVIN 92 215 2.337
TOMIC, ANTE 53 121 2.283
RIBAS, PAU 47 105 2.234
SINGLETON, CHRIS 26 63 2.423
CLAVER, VICTOR 23 58 2.522
KURIC, KYLE 21 48 2.286
ORIOLA, PIERRE 15 36 2.400
BLAZIC, JAKA 12 26 2.167
SERAPHIN, KEVIN 12 28 2.333

The last column of this data frame (ppa) tells us how many Points Per Assist each player from FC Barcelona generates (with at least 10 assists). We observe that Claver and Singleton generate the highest value per assist, indicating that a relatively high proportion of their assists lead to a three point shot.

#### Who assists who?

With play-by-play data, it is also possible to find out to whom each player’s assist go to. The ten most common combinations passer-shooter are shown below:

assists %>%
group_by(passer, shooter) %>%
count() %>%
arrange(desc(n)) %>%
head(10)
passer shooter n
HEURTEL, THOMAS SERAPHIN, KEVIN 27
HEURTEL, THOMAS TOMIC, ANTE 24
PANGOS, KEVIN TOMIC, ANTE 22
HEURTEL, THOMAS ORIOLA, PIERRE 21
HEURTEL, THOMAS SINGLETON, CHRIS 17
PANGOS, KEVIN KURIC, KYLE 16
PANGOS, KEVIN SERAPHIN, KEVIN 15
TOMIC, ANTE SINGLETON, CHRIS 15
HEURTEL, THOMAS CLAVER, VICTOR 12
HEURTEL, THOMAS KURIC, KYLE 12

The five most common combination passer-shooter are all from point guard to big man. We see that Heurtel connects very well with the bigs in his team, specially the two centers, Seraphin and Tomic. This explains the low proportion of assists to three point shots that we observed before.

However, in order to have a more accurate picture we would need to know how many minutes each combination was together on the floor. This information would allow us to identify potential improvements when deciding lineups.

#### How to visualize assists

It is possible to summarise some of the data that we obtained before using a heatmap showing the distribution of assists among the players of FC Barcelona. The function plot_heatmap() does just that:

plot_heatmap(pbp, "BAR") +
ggplot2::labs(
title = "FC Barcelona assist heatmap",
subtitle = "Euroleague 2018-2019 (first 28 games)",
x = "Shooter",
y = "Passer")

The vertical axis represents the passer while the horizontal axis represents the player that shoots after the pass. The diagonal contains the total number of assists for each player. The color indicates the number of assists that a given player gives to other player.