As the recently re-branded USL readies for its opener, the 24-team league is primed to challenge the NASL for title of second tier in the US soccer pyramidHe is the corollary to the effectiveness of the FC Dallas youth system. Hailing from right under the noses of club bosses near their Frisco base north of Dallas, Mikey Ambrose is the sort of development prospect garnering plaudits for the major league club.But the 21-year-old left back did something different from his cohorts.