By Matt Audilet Soon after Lincoln Riley left Oklahoma to take his new gig as the head coach of the USC Trojans, his former Sooners quarterback Caleb Williams followed him to Los Angeles. For the young QB to up his roots in Norman and join Riley on the West Coast, it’s clear they have a great deal of mutual respect. During an appearance with Trojans Liveon Tuesday, Williams cited Riley’s “magical” play-design ability as a main reason he chose to follow him to LA. “Obviously, we know his plays are — I mean, his plays are insane,” Williams said Tuesday on Trojans Live of why he made the decision…