ATLANTA Retired major leaguers who gathered for the Atlanta Braves alumni weekend noticed the pudginess of one former player. The middle-age man, who claimed to be former player John Sullivan, swung his bat remarkably slow during the alumni softball game during last weekends Braves reunion in Atlanta. We figured he mustve had some health problems, said former Braves reliever Jose Alvarez, who estimated the mans bat speed at no more than 30 mph. The mystery man, wearing No. 8, was never a Brave, The Atlanta Journal-Constitution reported. That didnt stop him from signing autographs for fans or attending a luncheon to honor John Smoltz, whose number was being retired. Former Braves manager Bobby Cox asked Greg McMichael, the retired Braves reliever, who the man was. John Sullivan, came the reply. I said, Thats not John Sullivan. I think youve been had, Cox said. When asked when he played for the Braves, the man responded, 1986 or 1987, Im not sure, Alvarez recalls. The man was gone by Sunday morning after being confronted by former players. The real John Sullivan, of Dansville, N.Y., said his wife would get a kick out of hearing the story.