Data Analysis on the Steroid Era in MLB
The skills demoed here can be learned through taking Data Science with Machine Learning bootcamp with NYC Data Science Academy.
Introduction
This is a quick look back at what is referred to as the Steroid ERA in baseball. Data shows starting in the mid 90's and going into the 2000's the MLB had some great home run races between hitters like Barry Bonds, Sammy Sosa, Mark McQuire, and Ken Griffey Jr. The hallowed mark of 61 homers was shattered after over 40 years of being untouchable.
Objective
The question is: What accounts for that dramatic rise in homeruns? Could it just be that we had some great hitters during that time? Or could it be a lively ball? Could it be rule changes, or umps calling a tighter strike zone? Can we chalk it up to smaller ball parks or more teams and diluted pitching?
My analysis, we are going to look at the time frame from 1995 - 2005 as the steroid ERA. No one knows for certain what years and which players To try to find the answers, we are going to look at the time frame from 1995 - 2005 as the steroid ERA. In fact, no one knows for certain which players took steroids. For our purposes, we’re relying on a list found here... from bleacher reports for the players on use of steroids. This is for comparison only -and not to point fingers at particula players.- I'll leave that to Jose Canseco (admitted user and writer of several books on players using steroids).
Let's start with a quick look back at baseball and home runs!
Background Data
The period prior to 1920 is known as the deadball period in baseball. Home runs were not a large part of the game until a man named Babe Ruth showed up. He started hitting the long ball just before the 20's and changed the way batters approached the game. Babe Ruth dominated baseball for 20 years, sometimes putting up more homeruns than many teams..
Home runs continued to rise in the sport until WWII when it dipped due to top talent serving in the war.After the 40's, home runs continued to rise until the 60's when rule changes impacted the game. “The year of the pitcher” was in 1968 r because the rules had changed so much that the pitchers dominated this time. MLB made changes to the rules like lowering the mound and lowering the strike zone.
After the 40's, homeruns continued to rise until the 60's when rule changes impacted the game. 1968 was called the year of the pitcher because the rules had changed so much, that the pitchers dominated this time. MLB made changes to the rules going forward, steps lowering the mound and lowering the strike zone.
Data
Sudden Increase
From 1994 until 2005, baseball had more batters hitting over 40 home runs per year than any other 10 year time in baseball. In fact, it was more than twice any other 10 year time period in baseball. (Chart below)
Continue Growth
From 1994 until 2005, baseball had more batters hitting over 40 homeruns per year than any other 10 year time in baseball. In fact, it was more than twice any other 10 year time period in baseball. (Chart below)
Below is the same chart scaling all batters to 500 at bats. It is still double any other 10 year period.
Age
The other remarkable oddity during this time is that the players were hitting home runs at an older age. Players extended their careers during this time by gaining strength as they aged. They also managed to stay healthier later in their careers.hey accomplished remarkable feats.
The left side of the chart shows career home runs. The bottom is HR after 31. Orange is finished career before 1994. Blue is finished or still playing after 1994. Players are hitting more home runs in their 30's than ever before.
Conclusion
My conclusion to all this is that it appears obvious that something was going on during this time. It may even still be going on (look up Nelson Cruz). When stats are scaled per at bat, number of teams, etc,. we still have more batters hitting over 40 home runs in a season during that time than any other time in history.
We had the 60 home run mark beaten 6 times during that time and only once in all the other years of baseball. During that time, 55 home runs were hit 11 times compared to 7 times total in all the years of baseball. Baseball parks didn't suddenly grow after that time. Players didn't start aging faster after that time period, and rules didn't suddenly change. It looks to me like the explanation we have, plus the number of players that have since admitted to or have been leaked from reports, shows the best explanation is stillsSteroids.
About Author
