IT'S SUPPOSED TO BE DIFFICULT. A Diamondback win in Chicago and a Brewer win in the final San Francisco game leave the Brewers 3 1/2 games ahead on July 22, with a 55-43 record. The earlier start to the season shows up in the comparative standings. In 1982, the Brewers, at 54-37, were 1/2 game ahead of Boston, and 5 games ahead of Baltimore, the team that ran out of season before it could catch up. When the North Shore Line was still running, the Braves, at 53-38, were a game ahead of St. Louis and Brooklyn and 2 ahead of Cincinnati. The Cubs were 21 1/2 games behind.