When Marlion Pickett runs onto the M.C.G for Richmond in the AFL Grand Final this Saturday, he’ll be only the sixth player in 124 finals to debut on the big day.

The sole purpose of this blog post is to illustrate how incredibly easy it is to figure this out, thanks to the dplyr and fitzRoy packages.

library(dplyr)
library(fitzRoy)

afldata <- get_afltables_stats()

afldata %>% 
  select(Season, Round, Date, ID, First.name, Surname, Playing.for, 
         Home.team, Home.score, Away.team, Away.score) %>% 
  group_by(ID) %>% 
  arrange(Date) %>%
  # a player's first game 
  slice(1) %>% 
  ungroup() %>% 
  # grand finals only
  filter(Round == "GF") %>%
  # get the winning/losing margin 
  mutate(Margin = case_when(Playing.for == Home.team ~ Home.score - Away.score,
                            TRUE ~ Away.score - Home.score)) %>% 
  select(-Home.team, -Away.team, Home.score, Away.score)