Posted on 21 September 2010.
The classic “back of the baseball card” offensive measures have always been batting average, home runs and RBIs, but the advanced stats explosion of the last 20+ years has exposed how limited those figures are. The main flaw with batting average is that it completely ignores plate appearances that result in a walk. RBI numbers are influenced heavily by something out of a player’s control: runners on base ahead of him. Home runs are of course great, but reflect only a tiny portion of how a player has fared at the plate.
Massively more telling metrics have been developed and are slowly gaining acceptance. On-base percentage (OBP) is a huge improvement over average since it includes plate appearances that end in a walk (and hit-by-pitch). It remains an incomplete measure, however, since it treats vastly different outcomes the same; as beneficial as walks are to an offense, they are obviously not worth as much as home runs, but OBP does not distinguish between them. Slugging gives different credit for various outcomes, but ignores walks and does not accurately weigh the different types of hits; a double is not worth twice as much as a single, a homer is not worth four times a single, etc. On-base plus slugging (OPS) attempts to make up for the flaws in OBP and slugging by adding them together, which results in a great stat. OPS does give a telling indication of how effective a hitter is. But it retains some of the flaws inherent to OBP and slugging, as well as putting too much weight on slugging relative to OBP.
Enter weighted on-base average, or wOBA. Developed by stats maven Tom Tango, wOBA is a near-perfect offensive stat. Through analysis that is over my head, Tango determined the relative benefit of walks, hit-by-pitches, reaching base on errors, singles, doubles, triples and home runs. He then scaled those relative weights such that the resulting stat is on the same scale as OBP. In Tango’s words, “an average hitter is around 0.340 or so, a great hitter is 0.400 or higher, and a poor hitter would be under 0.300.” The exact formula for wOBA is: (0.72xNIBB + 0.75xHBP + 0.90x1B + 0.92xRBOE + 1.24x2B + 1.56x3B + 1.95xHR) / PA. (FanGraphs.com lists wOBA.)
So wOBA is a beautiful thing. But as with any stat, comparing wOBAs from different seasons can be misleading, thanks to the yearly ups and downs in overall offense. In order to get numbers that can be compared across years, a player’s wOBA can be divided by that season’s league average wOBA to get an idea of how much more or less effective he was as a hitter than the rest of his league that year. To get to a wOBA+ stat, that number is multiplied by 100, meaning an exactly average wOBA performance results in a 100 wOBA+, a wOBA that is 10% better than league average results in a 110 wOBA+, and a wOBA 90% of league average results in a 90 wOBA+. The formula looks like this: 100 x (wOBA/lg avg wOBA).
Here’s a look at the 10 best wOBA+ seasons in Royals history (minimum 400 plate appearances):
1. George Brett ∙ 1980 ∙ 146 wOBA+
.479 wOBA/.390 AVG/.454 OBP/.664 SLG/203 OPS+
You don’t need advanced stats to know this was the greatest offensive season in Royals history. There’s no debate that 1980 George Brett was as good as it gets. Readers of this site appreciate the incredible talent of Albert Pujols, but Albert is yet to approach a wOBA of .479. (.462 in 2003 is his career high. Of course, Pujols’s .434 career wOBA dwarfs Brett’s .374.)
2. John Mayberry ∙ 1972 ∙ 136 wOBA+
.391 wOBA/.298 AVG/.394 OBP/.507 SLG/168 OPS+
3. John Mayberry ∙ 1975 ∙ 134 wOBA+
.427 wOBA/.291 AVG/.416 OBP/.547 SLG/168 OPS+
Big John Mayberry has an impressive three of the top six spots on this list. Mayberry terrorized AL pitching between 1972—75.
4. George Brett ∙ 1985 ∙ 133 wOBA+
.433 wOBA/.335 AVG/.436 OBP/.585 SLG/178 OPS+
Probably not a coincidence that George’s two best years are the same two years the Royals have gone to the World Series.
5. Danny Tartabull ∙ 1991 ∙ 132 wOBA+
.430 wOBA/.316 AVG/.397 OBP/.593 SLG/171 OPS+
Tartabull owns three of the top 21 wOBA+ years in Royals history. Wooly bully, wooly-bully…wooly-bully.
6. John Mayberry ∙ 1973 ∙ 126 wOBA+
.396 wOBA/.278 AVG/.417 OBP/.478 SLG/146 OPS+
7. Mike Fiore ∙ 1969 ∙ 126 wOBA+
.385 wOBA/.274 AVG/.420 OBP/.428 SLG/138 OPS+
This is the one surprise on the list for me. Fiore had played just six major-league games before the Royals scooped him up in the 1969 expansion draft. Thanks to the unimpressive batting average, my guess would be this excellent season went largely unnoticed in 1969 (though fans must have taken notice when he hit the first home run in Royals history on April 13). His .420 OBP remains the fifth highest in Royals history. Fiore would never put up even decent numbers again however, and the Royals shipped him to Boston in 1970. He was out of the majors after 1972. (One caveat to the pre-1973 seasons—the league average includes pitchers hitting stats, inflating wOBA+ for position players a bit.)
8. Amos Otis ∙ 1978 ∙ 126 wOBA+
.405 wOBA/.298 AVG/.380 OBP/.525 SLG/150 OPS+
This was the best of 10 incredible seasons A.O. put up between 1970—79.
9. Hal McRae ∙ 1976 ∙ 125 wOBA+
.395 wOBA/.332 AVG/.407 OBP/.461 SLG/153 OPS+
Hal McRae mashed for a bunch of years. He had at least 400 PAs between 1974—1983 and was above average every year. Seven times his wOBA+ was 110 or better, with three seasons of 120 or better.
10. George Brett ∙ 1983 ∙ 125 wOBA+
.407 wOBA/.310 AVG/.385 OBP/.563 SLG/158 OPS+
That guy was pretty good.