Great look for the CFL. He's been a standout coach up here in Canada for quite a while and making the jump directly to the NFL is a testament to the league's worth. As are guys like Brandon Browner( ex Calgary Stampeders star) and Cameron Wake( ex B.C. Lions star).
Trestman's pretty well heralded for his work with QB's. The guy he's coached in Montreal, Anthony Calvillo is one of the greatest QB's in the leagues history, and he's helped him keep producing under his tutelage. Also has done work with plenty of first rounders, including Jay Cutler, which is probably why the Bears liked him.