What is the Consistency Score? (Part I)

Ok let's get down to the nitty gritty of how my Consistency Score stat works.

It's origins come from the Similarity Score, invented by Bill James and widely popularized in recent years by Sean Forman of Baseball-Reference.com.

Let's start by talking about how the Similarity Score itself works. After that, in the next post, I'll break down how the Consistency Score work as a variation of the Similarity Score.

For starters, check out Sean's explanation of James' method for the Similarity Score right here.

In brief, the Similarity Score looks at the career totals for a player (can be active or retired) and compares them to the totals for another player. For each stat considered, the difference between the two totals is worth a certain number of points, and those points are subtracted from a starting value of 1000. There is also consideration of position, which is why the players most similar to a given player are usually those who played the same position.

Note that James' method does attempt to call any stats "good" or "bad." For example, differences in walks and strikeouts alike are assigned points that get subtracted from the total.

You'll have to refer back to James' original book to understand the exact reasons why he chose the stats he did, as well as why he assigned the number of points he did.

So, in short, the Similarity Score allows one to assign players a single number that characterizes how similar their careers are. This is useful when comparing career achievements or, by looking at Sim Scores part way through careers, in projecting how an active player's career might continue.

Read Part II to see how the Consistency Score works.