ARLINGTON HEIGHTS, Ill. − Considering that 140 trainers have started a runner at the 2013 Arlington meet, it’s a little hard to grasp how great an influence just two of them have cast over the proceedings. Wayne Catalano, with 26 wins, and Larry Rivelli, with 20, have combined to win 46 of the 192 races run. In other words, less than 2 percent of the trainer population has accounted for nearly one-quarter of the winners.