I moved to Texas in 1995, from Tennessee, and I followed Texas football because they were the big dog in the state. From 2000 to 2009 they were great and they started their mediocre run after the 2009 season. Sound familiar Vol fans. Anyway, the best players in Texas would commit to Texas in their junior year of high school. They didn't even have to leave the state to recruit the best players every year. Since 2009 they've pretty much been just like Tennessee----trying to find their way back and the best players in Texas have plenty of options these days. They aren't jumping on the Texas bandwagon like they used to.
Maybe not, but it's also because they haven't put a great product on the field.
In 2009, Texas took Garrett Gilbert, who was a 5 star QB. But he didn't pan out for them. In 2010, they took 3 star Case McCoy (obvious connection) and Connor Wood, both who were not elite. In 2011, they took a 3 star David Ash, who was not good. In 2012, they took Connor Brewer, who transferred within a year or two. In 2013, they took Tyrone Swoopes, who only played significant time in his sophomore year. In 2014, they took Jerrod Heard, who eventually transitioned to WR. In 2015, they took 3 star Matthew Merrick. Just a disaster run of QB's.
In the meantime, between 2009 and 2015, while maybe not as highly rated, James Franklin, Johnny Manziel (although he had ties to A&M), Trevone Boykin, Trevor Knight, J.T. Barrett, Baker Mayfield, Patrick Mahomes, Kyler Murray, Jarrett Stidham all from Texas who went to other schools and had some success. They also apparently didn't try to solve the problem by looking outside the state. Additionally, it became cumulative with the rest of recruiting. Because QB play was poor and not developed, then Texas didn't get one recruit in the state's top 9 in 2015.
I think we all know what bad QB play can do to a program, and to me, it has all started there for Texas since 2009. If they had a dynamic QB, plenty of Texas players would be jumping on the bandwagon.