AUSTIN -- Texas may have finally found an answer at quarterback.Freshman David Ash and sophomore Case McCoy relieved struggling starter Garrett Gilbert in the second quarter and combined to resurrect the Longhorns' dormant offense en route to a 17-16 win over Brigham Young on Saturday night at Darrell K Royal-Texas Memorial Stadium.Texas rallied from a 13-point hole after Gilbert was benched following the Longhorns' first drive of the second quarter. The junior, who won the quarterback battle in fall camp and started the Longhorns' last 14 games, threw two interceptions and completed just 2 of 8 attempts for 8 yards.The Longhorns' first five possessions resulted in two turnovers and three three-and-outs. After starting out slowly for the second time in as many weeks, co-offensive coordinator Bryan Harsin decided it was time to make a switch at quarterback in hopes of igniting the offense."We weren't off to the start we wanted to have," Harsin said. "So we just needed to provide a spark, and Case did a good job of doing that and David did a good job. We got the momentum and got going."Ash ran the ball effectively and made smart reads on the option, rushing for 36 yards on nine carries. He rotated every few snaps with McCoy, who came onto the field in passing situations."David did a fantastic job of running the ball and being physical," Harsin said. "He took some shots and hung onto the football and that's really what we all wanted to see."McCoy made the most of his opportunities and completed 7 of 8 passes for 57 yards, including a pair of crucial strikes to Jaxon Shipley during an eight-play, 52-yard scoring drive that gave Texas the lead in the fourth quarter."I felt like our team rallied around me and David," McCoy said.While Texas got off to a sluggish start, BYU was sharp from the opening kickoff. The Cougars scored on each of their first two possessions, but the Longhorns defense shored up in the red zone and limited the visitors to field goals."We started changing up the coverage a little bit," said linebacker Emmanuel Acho. "We finally got a feel of what they were doing and where they were going to pass. We adjusted well."The defense kept the game close and the Longhorns eventually found some success moving the ball in the second half.The Longhorns came out of halftime with a passion that was lacking in the first half. Texas forced a three-and-out and then promptly marched downfield for a 7-play, 62-yard scoring drive capped off by Cody Johnson's 1-yard TD run to cut the BYU lead to 13-10.With Ash and McCoy constantly rotating, the Longhorns kept the Cougars defense on its heels. Ash used his mobility and athleticism to move the chains with his legs, providing a change of pace from McCoy."It's a tempo change, something the defense doesn't think about," Ash said.The Longhorns' young secondary was tested early and often, and looked shaky in the first half as the Cougars passed for 153 yards and a touchdown. They made plays when they needed it most, though, as freshman corner Quandre Diggs intercepted BYU's Jake Heaps at the Texas 43 with 3:39 to play to seal the win for the Longhorns.Freshman running back Malcolm Brown led Texas in rushing for the second straight game, carrying 14 times for 68 yards.