Great football players are seldom defined by any physical testing numbers. Still, eye-catching 40 times or vertical-jump measurements often help turn a four-star recruit into a five-star guy. Last summer when freshman Derek Barnett arrived in Knoxville, he came to Tennessee as a blue-chip prospect, but was hardly one of the more hyped recruits in UT's class, much less in the SEC's freshman crop.Vols coach Butch Jones thought Barnett had a chance to be an impact guy for his rebuilding program, but admits he didn't realize quite what he had until about UT's second week of fall practice last August. The Vols were in a "thud" situation during one of their practice periods when Jalen Hurd, their five-star freshman running back, broke out of a cluster around the line of scrimmage and took off down the right sidelines. Jones and the rest of his staff were stunned when they spotted Barnett, a 6-foot-3, 270-pound blur fly in from the opposite side of the field to blast Hurd.