Plots career trajectories for several pitchers nominated for the Hall of Fame in 2017

HOF_trajectories.R

get_data <- function(pitcher){
    require(Lahman)
    require(dplyr)
    get.birthyear <- function(player.id){
       playerline <- filter(Master, playerID == player.id)
       birthyear <- playerline$birthYear
       birthmonth <- playerline$birthMonth
       ifelse(birthmonth >= 7, birthyear + 1, birthyear)
     }
    names <- unlist(strsplit(pitcher, " "))
    id <- filter(Master,
      nameFirst==names[1], nameLast==names[2])$playerID
    filter(Pitching, playerID==id) %>%
      mutate(Age = yearID - get.birthyear(id)) -> d
      summarize(group_by(d, yearID),
      Age = first(Age), IPouts = sum(IPouts),
      H = sum(H), BB = sum(BB), SO = sum(SO),
      HR = sum(HR), HBP = sum(HBP),
      W = sum(W), L = sum(L))
}

pdata <- rbind(data.frame(Player="Clemens",
               get_data("Roger Clemens")),
          data.frame(Player="Mussina",
               get_data("Mike Mussina")),
          data.frame(Player="Schilling",
               get_data("Curt Schilling")),
          data.frame(Player="Maddux",
               get_data("Greg Maddux")),
          data.frame(Player="Smoltz",
               get_data("John Smoltz")),
          data.frame(Player="Glavine",
               get_data("Tom Glavine")))

pdata <- mutate(pdata, WHIP = (H + BB) / (IPouts / 3),
                SO.Rate = SO / (IPouts / 3),
                FIP=(13 * HR + 3 * (BB + HBP) - 2 * SO) /
                  (IPouts / 3),
                Win_PCT = 100 * W / (W + L))

library(ggplot2)
library(ggthemes)
TH <- theme(
  plot.title = element_text(
    colour = "blue",
    size = 18,
    hjust = 0.5,
    vjust = 0.8,
    angle = 0
  )
)
ggplot(pdata, aes(Age, Win_PCT)) +
  geom_point() +
  geom_smooth() +
  ylim(30, 90) +
  facet_wrap(~ Player, ncol=2) +
  theme_solarized() +
  ggtitle("Win Percentage Trajectories") + TH

ggplot(pdata, aes(Age, WHIP)) +
  geom_point() +
  geom_smooth() +
  facet_wrap(~ Player, ncol=2) +
  ylim(.8, 1.6) +
  theme_solarized() +
  ggtitle("WHIP Trajectories") + TH

ggplot(pdata, aes(Age, SO.Rate)) +
  geom_point() +
  geom_smooth() +
  facet_wrap(~ Player, ncol=2) +
  ylim(.5, 1.25) +
  theme_solarized() +
  ggtitle("SO Rate Trajectories") + TH

ggplot(pdata, aes(Age, FIP)) +
  geom_point() +
  geom_smooth() +
  facet_wrap(~ Player, ncol=2) +
  ylim(-1, 2) +
  theme_solarized() +
  ggtitle("FIP Trajectories") + TH