When you announce you're casting a sports film, suddenly every pretty-boy actor with a Crunch membership claims he's the next LeBron James. That's because ''actors are full of s---,'' says Brian Robbins, exec producer of the WB hoops drama One Tree Hill. So when Chad Michael Murray needed a can't-miss jump shot for Hill, Robbins called on ReelSports Solutions, a South Carolina-based consulting firm that's become the McKinsey of sweat-stained celluloid. Founded in 2001 by former college gridiron teammates Mark Ellis and Rob Miller, ReelSports has played ball with Dennis Quaid for The Rookie, Bernie Mac for Mr. 3000, and Dean Cain for CBS' Clubhouse. Having just taught Adam Sandler to throw a spiral for the May 2005 remake of The Longest Yard, Ellis is now working passing drills with Sandler's costar Nelly. Not that the rapper needs the coaching, mind you. ''I played ball in high school, so I'm just havin' fun,'' says Nelly. ''Adam's got a pretty good arm, but he works hard.''