[mcgwirecom]

OK I found the reason....

As champions of the National League, the Padres had home-field advantage. But had the Chicago Cubs won the NLCS (which appeared likely after the Cubs took a 2–0 lead in the best-of-five series), the Tigers would have gained home-field advantage despite the fact the AL's Baltimore Orioles had it the season before. NBC was contractually obligated to show all midweek series games in prime time, something that would have been impossible at Wrigley Field, since the Cubs' venerable facility lacked lights at the time (they would not install lights until four years later). Had the Cubs advanced to the Series, Detroit would have hosted Games 1, 2, 6 and 7 (on Tuesday and Wednesday nights), while the Cubs would have hosted Games 3, 4 and 5 (on Friday, Saturday and Sunday), with all three games in Chicago starting no later than 1:30 p.m. Central time.