Baseball’s basic statistics can mean different things in different playing conditions.
A .300 batting average doesn’t mean the same thing in 2019, when the MLB average is .251, as it did in 1930 (.296, including .306 in the National League) or 1908 (.239).
Modern metrics help put things in context and ease a comparison among players who faced different conditions.
One way is through + stats, which you can find on Fangraphs.com’s leaders pages.
The + stats adjust for ballparks, compare to other players in the same season and normalize so 100 represents average. One of the best comparisons going is weighted runs created plus, whereby Kris Bryant’s 144 wRC+ tells you he has been 144 percent as productive as an average player in his total offensive game.
But + stats don’t have to be as all-inclusive or as complex as wRC+. If all you want is to put batting average into context, Fangraphs offers AVG+. It also lists + stats for strikeout and walk percentages, slugging percentage, on-base percentage and more.
A couple of examples:
AVG+: Catcher James McCann leads the White Sox with a .319 batting average, with shortstop Tim Anderson right behind at .317.
On the surface, those are in the same ballpark as the .320 by the Tigers’ Marty McManus and the Pirates’ Dick Bartell but under the hitter-friendly conditions of 1930. McManus’ AVG+ was 109, and Bartell’s was 102. Neither was as far above the average hitters of their time as McCann (127) and Anderson (126).
How high would a 1930 average need to be to match the pair of Sox? The Brooklyn Robins’ Babe Herman was at 126 with a .393 average.
Conversely, in the 1968 Year of the Pitcher, the Red Sox’ Carl Yastrzemski’s .301 BA led the American League and was worth a 126 AVG+.
That’s a wide range of averages to put into context. McCann’s .319, Herman’s .393 and Yastrzemski’s .301 rank about the same when adjusted for conditions and league averages.
ISO+: Isolated power measures the portion of slugging percentage that comes from extra bases. It subtracts batting average from slugging percentage.
The Cubs’ ISO leaders entering Monday were catcher Willson Contreras at .272 and shortstop Javy Baez at .262 (18th and 23rd in MLB). We’re in an era that favors ISO, especially home runs. The ISO for MLB in 2019 of .179 would break the record of .171 set in 2017. It’s far above the .130 of 1930, let alone the .066 of 1908.
Contreras at 147 and Baez at 142 have shown more than 40 percent more isolated power than an average hitter of 2019. In 1930, Lefty O’Doul had a 144 ISO+ with a .222 ISO. In the dead ball days of 1908, the Pirates’ Fred Clarke had a 138 ISO+, not far behind Baez, but with 37 percent of the ISO at .098.
Raw stats mean different things in different eras, but they can be put in context for cross-era comparisons. And that’s a + for fans.
