For the fourth time in the 45-year history of the Foot Locker Cross-Country Championships, the national title is coming home to Massachusetts. After vaulting into the lead on the grueling uphill stretch at the race’s 2.5-mile mark, Phillips Academy Andover senior Tam Gavenas cruised down the backstretch to claim the national championship in 15 minutes, 23.9 seconds at Balboa Park in San Diego.