With 55 doubles, Brian Roberts is tied with Lance Berkman and Gee Walker for 18th on the all-time, single season doubles list. His next double will be number 56 and that would tie him for 13th best all-time. If he gets 57, he'll move into the all-time top ten for one season.
Craig Biggio, 1999
Garret Anderson, 2002
Nomar Garciaparra, 2002
George Kell, 1950
Joe Medwick, 1937
Carlos Delgado, 2000
Billy Herman, 1935
Billy Herman, 1936
So Roberts next double will be number 56 and no one has had that many in the Majors since 2002.
The record for doubles in one season by a second baseman is Charlie Gehringer, 60, in 1936. The all-time record for one year is held by Earl Webb, who hit 67 in 1931.
Roberts, doubles by month, 2009:
He hit 29 doubles in 86 games in the first half and has hit 26 in 63 games in the second half.