Bruce Arians played the Cardinals’ main room on Friday during his introduction as the team’s new head coach. Days earlier, Ray Horton slipped away quietly out of the team facility, never to return again. And as the cliché goes, the split is probably best for everyone, including those left behind. Arians is able to bring in his own defensive coordinator, most likely Eagles assistant Todd Bowles. And Horton doesn’t have to work for someone (Arians), who has the job he coveted.