Baker Mayfield, believed to be the first walk-on true freshman quarterback to start a season opener for a BCS school, accounted for five touchdowns in a 41-23 victory over SMU on Friday night in the Red Raiders' first game under Kliff Kingsbury, at 34 the youngest head coach at a BCS school. [...] most of that — three TD passes and the scoring run — came after SMU opened the second half with a drive that ended with a missed 27-yard field goal only two plays after a touchdown scramble by Garrett Gilbert was wiped out by a holding call. Mayfield certainly seemed at ease under the Friday night lights — just like the past two seasons as a starter at Lake Travis High School in Austin, Texas, while winning a state championship. Last season, he was Texas A&M's offensive coordinator with Heisman Trophy-winning freshman quarterback Johnny Manziel. The last time Texas Tech has played a regular season game on a Friday was in 2002, when Kingsbury threw for 407 yards and six touchdowns in a 49-0 win at New Mexico. Gilbert transferred to SMU from Texas, where he played in the BCS championship game as a freshman four seasons ago against Alabama when he took over for an injured Colt McCoy.