March 1, 2013

Sabermetric Averages

One of my complaints about writers who talk about Sabermetrics is that they don't talk about what the league average is for the specific stat they use. In fact I believe one of biggest misses Sabermetric writers have made is not explaining what the average is for a specific stat. People still cling to Batting Average because they know someone with a .280 BA is a average player and anything else higher is good.

Well that ends here today. A few years ago Fangraphs posted the entire glossary of the sabermetric stats they use with the averages. I'll be posting a quick explanation of what the stat is and the average. Well I'll be using the average Fangraphs posted and try to explain what they said. So many thanks to Fangraphs for the information. (Note: League average varies from year to year but this will give you idea of what an average player should be hitting.)

On Base Percentage (OBP): How good a player is at not making outs.
Average: .320

On Base plus Slugging (OPS): How good a player is at not making outs plus their slugging percentage.
Average: 0.730

Weighted On-Base Average (wOBA): Unlike OBP which assumes all hits are created equal, wOBA weighs all hits differently and spits them out into one beautiful number. Secretly the most important stat for hitters.
Average: .320

Weighted Runs Above Average (wRAA): Basically a stat that gives you an idea of how valuable a hitter is because of how many runs a player creates. A player with a 0 wRAA is league average and everything above that is good.
Average: 0

Weighted Runs Created (wRC+): A stat used to see how players created or not created runs against the average player.
Average: 100

Batting Average On Balls In Play (BABIP): Basically a measure for a player's luck at hitting. BABIP is admittedly a goofy stat that I don't pay a lot of attention to. For example, Tony Gwynn had a career .341 BABIP. He wasn't lucky, he was just good at hitting. So this is a grain of salt stat basically. Look at who the player is before taking it seriously.
Average: Between .290 and .310

Isolated Power (ISO): A measure to see how good a player is at hitting extra base hits (HR's, Doubles, Triples).
Average: 0.145

Home Runs per Fly Ball rate (HR/FB): A context stat about how sustainable HR power is.
Average: 9.5%

Strikeout and Walk percentage (K% and BB%): As simple as it sounds. How often does a player strikeout or walk per plate appearance.
Average: 18.5 K% & 8.5 BB%

Plate Discipline
Outside Swing Percentage (O-Swing%): The percentage the batter swings as pitches outside of the strike zone.
Average: 30%

Inside-Strike Zone Percentage (Z-Swing%): The percentage the batter swings at inside the strike zone.
Average: 65%

Contact Percentage (Contact %): The overall contact the batter makes.
Average: 81%

Zone Percentage (Zone%): The overall percentage of pitches a batter sees inside the strike zone.
Average: 45%

Revised Zone Rating (RZR): The proportion of balls hit to a fielder that he successfully converts into an out.
Average: 0.835

Ultimate Zone Rating (UZR): A stat to quantify a player's defensive contributions. There's more to than that, so go to Fangraphs and read up on UZR.
Average: 0

Skill-Interactive ERA (SIERA): I use SIERA over the FIP's because it's a more accurate model of how good a pitcher is.
Average: 3.90

Strikeout and Walk Rates (K% & BB%): Pitchers strikeout and walk rate.
Averages: 7.1 K/9 & 3.3 BB/9

Batting Average on Balls in Play (BABIP): Measures how many balls in play will land for hits against a pitcher. Like hitting BABIP, look at who the pitcher is before freaking out over their BABIP.
Average: Between .290 and .300

Win Probability
Win Probability Added (WPA): Measures a players affect their team's chances at winning a game per-play basis.
Average: +1.0

Clutch: How well does a player perform in high leverage situations?
Average: 0.0

Wins Above Replacement (WAR): The EVIL WAR statistic! It's the scourge of the underworld that is advance metrics! Actually it's just a stat that measures how good a player is overall. Example: The Angels would have been 10 wins worse last year theoretically if Mike Trout wasn't in their lineup. Now that's valuable.
Average: 1-2 WAR

Now there are a lot more stats at Fangraphs with more thorough explanations than these ones. Seriously go to their glossary and learn about baseball. This post will be in the sidebar of this blog for you can access it easily.

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