Mark DeRosa came into Friday's game against the Rockies hitting .308 with a batting line (OBP/SLG/OPS) of 400/453/853 and an OPS+ of 121. If he were to finish the season with those numbers, he would establish career highs for batting average, on-base percentage, and OPS, and the Cubs would seem to be getting good value for their $4.75MM.
Still, according to another metric, DeRosa has been the least effective offensive player on the '08 Cubs. Fangraphs, a site I refer to and link to often, measured DeRosa's cumulative Win Probability Added before today at -.72. (By comparison, Aramis Ramirez led the team at +2.42 with Kosuke Fukudome second at +1.42.)
Today's stunning 10-9 Cub win over Colorado at Wrigley Field will take its place in the Big Book of Unbelievable Cub Comebacks; it also did wonders for DeRosa's WPA number. DeRo's two-run, seventh-inning homer off of woebegone Rox reliever Manny Corpas which put the Cubs in front to stay, 10-9, increased the Cubs' probability of winning from 40.9% to 76.7% and boosted DeRosa's personal WPA by a whopping .358. It was far and away his most impactful hit of the season.
And many, many Cub fans in every corner of the baseball-loving world, most of whom haven't heard of Win Probability Added, will never forget it.