Last week, Roberto Alomar and Bert Blyleven were elected to Baseball's Hall of Fame (HOF). Actually, what is most interesting about this sports story are the players who did not get elected for this special honor.
Players get elected to the Hall of Fame primarily by the Baseball Writers Association of America (BBWAA). Writers in the BBWAA are given a ballot of 24-40 candidates and each is allowed to cast votes for at most 10 players. Any player who receives votes from at least 75% of the writers is elected to the HOF.
Some famous baseball sluggers only received a small percentage of votes including Jeff Bagwell (41.7%), Mark McGwire (19.8) and Rafael Palmeiro (11.0%). McGwire had 583 career home runs (the 10th most in history) and had the second most home runs in a single season (70 in 1998). Palmeiro and Bagwell had respectively the 12th and 34th most career home runs in history. (See this web site for a complete list.)
Why didn't these great sluggers get more HOF votes from the writers? All three of these players played during the so-called steroid era in baseball where many ballplayers are believed to take illegal performance-enhancing drugs.
Did the use of steroids really enhance players' batting abilities during this period of baseball? One way to address this question is to collect home run hitting statistics over the history of baseball and see if one can detect an increase in home run hitting over this period. The relevant data can be found from baseball-reference.com.
The graph below plots the average number of home runs hit by each team per game for the seasons 1970 through 2010. To see the basic pattern, a lowess smoothing curve is placed on top. Three points are labeled - these correspond to three notable years in baseball. Ken Caminiti (the 1996 National League Most Valuable Player) admitted to using steroids in the 1996 season. In 1998, Mark McGwire and Sammy Sosa both broke the current season home run record, and in 2001 Barry Bonds obtained the current season home run record with 73.
It is pretty clear from the graph that there was a big increase in home run hitting about 1994. The pattern of home run hitting stayed relatively constant for ten years and the average number of home runs has very recently decreased. This period of great home run hitting approximately corresponds to the period where steroid use is believed to be prevelant in baseball.
One interesting question is how the baseball world views players such as Mark McGwire who obtained great batting records during this period. Should we adjust McGwire home run records by dividing by some "steriod factor"? Judging by the votes, some people currently believe that McGwire should be excluded from the HOF. This debate will continue, especially when Barry Bonds (the greatest home run slugger) is eligible for the Hall of Fame election next December.