Manny Pacquiao’s return to the ring last weekend after a four-year hiatus marked the latest example of a boxer well past his prime who could not resist the temptation of the squared circle and a chance to add to his competitive legacy. The 46-year-old Filipino came out of retirement on Saturday to fight Mario Barrios in Las Vegas but fell short of breaking his own record as the oldest-ever welterweight champion, as the American boxer escaped with a majority draw. Fights involving boxers such as...