Baseball Stats for Dummies Part 4: OPS+

[JoeH33]

OPS+ is another stat that I see thrown around occasionally at this site. If I recall correctly, I believe it is a stat that uses 100 as the league average, so if you have an OPS+ of say 125 you're having a good year.

 

My question is, how do you calculate this stat and how exactly do you use it? Is it more valuable of a stat than OPS?

[rluzinski]

My question is, how do you calculate this stat

 

From baseball-reference.com:

 

Quote:

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Adjusted OPS. Essentially OPS normalized to the league. Think of it as a rate above the league average expressed as a percentage.

 

1. Compute the runs created for the league with pitchers removed (basic form) RC = (H + BB + HBP)*(TB)/(AB + BB + HBP + SF)

 

2. Adjust this by the park factor RC' = RC*BPF

 

3. Assume that if hits increase in a park, that BB, HBP, TB increase at the some proportion.

 

4. Assume that Outs = AB - H (more or less) do not change at all as outs are finite.

 

5. Compute the number of H, BB, HBP, TB needed to produce RC', involves the quadratic formula. The idea for this came from the Willie Davis player comment in the Bill James New Historical Baseball Abstract. I think some others, including Clay Davenport have done some similar things.

 

6. Using these adjusted values compute what the league average player would have hit lgOBP*, lgSLG* in a park.

 

7. Take OPS+ = 100 * (OBP/lgOBP* + SLG/lgSLG* - 1)

 

8.Note, in my database, I don't store lgSLG, but store lgTB and similarly for lgOBP and lg(Times on Base), this makes calculation of career OPS+ much easier

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and how exactly do you use it?

 

It allows for comparison of players from diffrent teams and/or different years. A .750 OPS from Colorado in 1999 isn't very good at all and OPS+ would expose that.