Wall Street Journal Book Review Seems To Have Error About 1919 White Sox

See Was It So, Shoeless Joe? Here is the letter I sent them:

"David M. Shribman's review of "The Betrayal" by Charles Fountain ("Was It So, Shoeless Joe?" Oct. 31) seems to have a major statistical error. It reads "In the Series they (the White Sox) batted .255, significantly higher than their .215 season average." But Baseball Reference shows the White Sox to have a team batting average of .287 during the 1919 season while batting just .224 during the World Series.
http://www.baseball-reference.com/postseason/1919_WS.shtml"