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Recent wisdom, gossip and conjecture:
Breaking Down the Batting Stats
There are no doubt some of you out there wondering about all these stats that we throw at you sometimes. We thought it was about time we gave you a quick overview of the all the major stat categories -- how they're calculated and what useful information you can glean from them. As an added bonus, I'll even point out some weaknesses.
Batting Average (AVG or BA)
How to calculate: Hits / At Bats
AVG is the traditional indication of batter quality, but it's overrated as a measure of how good a hitter is. Because the great hitters had high averages, it doesn't mean that every high average hitter is great. Ted Williams had high AVG, high OBP and high SLG. It was the latter two that made him great, not so much the first.
If you were to gauge a hitter by only one common stat, it should be on-base percentage, not batting average.
On-Base Percentage (OBP or OBA)
How to calculate: (H + BB + HBP) / (AB + BB + HBP + SF)
OBP measures the ability to hit and take a walk, but doesn't include extra-base power.
Slugging Average (SLG)
How to calculate: Total Bases / At Bats
SLG is a good indication of a batter's power. It doesn't account for walks.
On Base Plus Slugging (OPS)
How to calculate: OBP + SLG
OPS is an excellent measure of all-around batting ability -- the ability to produce runs.
It's easy to calculate, as OBP and SLG are now available from many sources. However, it doesn't include baserunning ability (or lack of it) and slightly overvalues SLG at the expense of OBP.
Total Average (TA)
How to calculate: ([TB + HBP + BB+SB] - CS)/([AB - H] + CS + DP)
Total Average is a good indicator of all around offensive ability, including base stealing. It does require at least basic math skills, however, and they just aren't that common any more.
Runs Created per 25 outs (RC/25)
How to calculate:
A = H + BB - CS
B = TB + .64 * SB + .24 * BB - .03 * K
C = AB + BB
RC = A * B / C
O = AB - H + CS
RC/25 = RC / O * 25
A simplified version of RC/27, created by Bill James to measure run production when some data needed for RC/27 is unavailable, typically during the season.
This stat measures offensive production very well. Note that it includes stolen bases and caught stealing, as well as minor adjustments for strikeouts. Well, it isn't easy to collect all the information you need just to do the calculation in the first place, then it's pretty difficult to do the math in your head. Overall we're looking at a stat that needs a lot of dedication and love from the people who use it.
It's only marginally more accurate an indicator than OPS.
Runs Created per 27 outs (RC/27)
How to calculate: Do you really want to know?
A = (H+BB+HBP-CS-GIDP)
B = .26(TB-IBB+HBP)
C = .52(SH+SF+SB)
D = (AB+TBB+HBP+SH+SF)
RC = A * (TB+B+C) / D
RC/27 = RC * (3 * League Outs / League Team Games) / Outs Made
Is that clear? All the above for RC/25 and then some.
As an evaluative tool (i.e. looking back at a season), it's an excellent way to measure who contributed the most with the bat. Even more data and calculating are required, and again, it's only marginally more accurate than OPS.
As a predictive tool, it's probably no better than OPS, due to the inherent random fluctuations of player performance from season to season.
It lacks a factor for that all-important clubhouse leadership (that's a joke, people...)
|about the author|
Dave Paisley is currently playing on Broadway in the title role of the Andrew Lloyd Webber hit, "Bill James: The Musical."