The Arizona Republic spoke with Jason Grimsley's attorney and said that Grimsley was targeted because he would not cooperate with Federal investigations about Barry Bonds.
"It was a specific effort to target Bonds," said Edward F. Novak, one of the pre-eminent criminal attorneys in Arizona. "We were told that Jason's cooperation was necessary to their case."
Novak said Grimsley "was outed by the feds" because he refused to cooperate.
Interestingly (to me at least), Barry Bonds was 0 for 7 in his career against Jason Grimsley, although he did draw two walks.
The only pitchers that Bonds fared worse against (in the sense of having more at bats) were Charlie Puleo and Tim Wakefield, both of whom had 0 for 8 records against Bonds.
The Grimsley story also gives pretty much everybody the chance to use "the local angle". This is Grimsley's transactions history from Baseball Reference.com
June 3, 1985: Drafted by the Philadelphia Phillies in the 10th round of the 1985 amateur draft.
April 2, 1992: Traded by the Philadelphia Phillies to the Houston Astros for Curt Schilling.
March 30, 1993: Released by the Houston Astros.
April 7, 1993: Signed as a Free Agent with the Cleveland Indians.
February 15, 1996: Traded by the Cleveland Indians with Pep Harris to the California Angels for Brian Anderson.
October 8, 1996: Granted Free Agency.
January 17, 1997: Signed as a Free Agent with the Detroit Tigers.
March 20, 1997: Released by the Detroit Tigers.
April 3, 1997: Signed as a Free Agent with the Milwaukee Brewers.
July 29, 1997: Traded by the Milwaukee Brewers to the Kansas City Royals for Jamie Brewington.
October 15, 1997: Granted Free Agency.
January 8, 1998: Signed as a Free Agent with the Cleveland Indians.
October 15, 1998: Granted Free Agency.
January 26, 1999: Signed as a Free Agent with the New York Yankees.
November 20, 2000: Released by the New York Yankees.
January 19, 2001: Signed as a Free Agent with the Kansas City Royals.
October 29, 2003: Granted Free Agency.
December 7, 2003: Signed as a Free Agent with the Kansas City Royals.
June 21, 2004: Traded by the Kansas City Royals to the Baltimore Orioles for Denny Bautista.
January 13, 2005: Signed free agent RHP Jason Grimsley to a one-year contract. (This one was from MLB.com, I don't have the date the Orioles made Grimsley a free agent, but presumably it was after the World Series ended.)