Hi, I’m Average

In the statistical community, you’ll generally see two baselines for metrics that compare players one to another – average and replacement level. There have been a lot of arguments about what replacement level is, whether it’s the same for each position, and whether or not it works for every team. However, most people generally don’t quibble with above average metrics, because the concept of average is taught in third grade math. Everyone knows what average is.

But what does average look like? When we talk about contribution over an average player, who are we talking about? Who is the personification of average production in MLB?

For 2008, one man stands above the rest – the most consistently average player in baseball. That man is Kelly Johnson.

His batting average is .266, compared to a league average of .259.
His on base percentage is .335, compared to a league average of .330.
His slugging percentage is .416, compared to a league average of .413.

He’s posting an average BB/K rate, an average ISO, and an average BABIP. His WPA/LI (which is measured as above average) is -0.01. He’s even average defensively, as the Fielding Bible +/- system ranks him as just +3 plays as a second baseman, which is not quite a premium position but not a spot for oafs either.

You name the skill, Johnson is probably about league average at it. So, the next time you hear someone refer to runs or wins above average, feel free to reinterpret it as runs or wins above Kelly Johnson.