To judge New York Fashion Week by the lineup at Thursday night's Fashion Rocks concert, you'd think the mismatched look was in.Fergie sang with Aerosmith, Teri Hatcher shared the stage with 50 Cent to introduce Jennifer Lopez, and Jeremy Piven served as host to a crowd of style insiders. From the start, Piven wondered aloud why he was there — were possible emcees Tom Ford, Kanye West or Heidi Klum all unavailable?Yes, Piven answered, and that left him to do the job. He was more than serviceable.He warmed up the crowd at Radio City Musical Hall with photos of the "trendsetting" fashions of his youth. The oversize T-shirts that now dominate designer runways — check. Feathered hair later worn by Kristy McNichol and more recently by the heartthrobs on the "O.C." — check.Same goes for Jean Paul Gaultier's crazy hats and shawls. Piven compared them to the outfit he wore to his bar mitzvah.He did better for Fashion Rocks in a slightly shiny dark suit. But some of the other celebrities onstage more closely hit the fashion mark: Martina McBride wore a pantsuit and bow blouse in line with the fall's polished look, and Cuba Gooding Jr., with a bright yellow shirt, must have had an early line on the spring clothes being previewed on the catwalks through Wednesday.Steven Tyler wore a medley of animal prints, Jessica Alba had on a black gown with chain link detail and Tyra Banks wore on-trend booties with her black cocktail dress. Lopez started her performance in a short, sequined trenchcoat but eventually pulled it off to reveal a short, sequined baby-doll dress. She kept her knee-high boots on the whole time.