LAS VEGAS — Tigers slugger Cecil Fielder entered the last regular-season game in 1990 with 49 home runs. The Caesars Palace sportsbook had posted a seasonlong MLB proposition of 50½ dingers. George Foster had last cracked the 50 barrier with 52 for the Reds in 1977. Like clockwork, the sports-betting-radio figure kept buying “NO” tickets that summer. Vinny Magliulo, who ran that book, spreads his right index finger half an inch from the thumb an…