STOCKTON — Sierra got a good gauge for the Valley Oak League competition to come Tuesday, dominating the second half for a 3-1 win at Lincoln.The Trojans (5-4) have wins over Weston Ranch, Manteca and East Union but could not keep the unbeaten VOL champion at bay. Sierra (9-0-1) netted three unanswered goals and did not allow a shot in the second half. Jadyn Shinn scored the go-ahead and insurance goals in the second half, and goalie Michaela Bitle finished with five saves.“We brought the energy in the second half after starting pretty flat,” Sierra coach Manuel Pires said.The Timberwolves did not get on board until Jenna Villanueva converted with a 20-yard blast in the 33rd minute.“Jenna is only a freshman but she controls the middle for our team,” Pires said.