The president of Arlington Park, Roy Arnold, has resigned, the track&rsquo;s owner, Churchill Downs Inc., announced Monday.\r\nArnold&rsquo;s resignation is effective immediately, but he will stay on as a consultant during &ldquo;a transition period,&rdquo; according to a press release. Churchill Downs Inc. has not yet named Arnold&rsquo;s replacement.\r\nArnold said in the release that he was leaving &ldquo;to explore new challenges and opportunities.&rdquo;\r\nBefore coming to Arlington in April 2006, Arnold spent 30 years in the United States military, where he reached the rank of Marine colonel. He brought no horse racing experience to the Arlington position, a fact that probably contributed to the frequent criticism directed at Arnold from local horsemen. This past summer, Arnold took the unusual step of trying to cancel a $100,000 stakes the day it was to be run. The race had been moved from turf to Polytrack, resulting in a series of scratches that produced a very short field.\r\nArnold has presided over the four years of Arlington&rsquo;s Polytrack era, a period that has seen startling declines in all-sources handle on the local racing product. Arlington experienced a 27-percent average-daily all-sources handle decline this year alone, and the daily average handle on Arlington races has dropped almost 38 percent since 2007.\r\nAttendance and ontrack handle have fared better in recent seasons, and Arlington to some extent was caught up in negative national trends.