Posted by ESPN.com's Adam Rittenberg
As players filter in and out of football programs, certain position groups become grizzled or green. As the St. Patrick's Day series marches on, it's time to look at the greenest, or least experienced, units on every Big Ten squad heading into 2009.
Illinois' defensive line -- Mainstays Will Davis, Derek Walker and David Lindquist depart, and with Josh Brent's status up in the air, Illinois looks unproven up front.
Indiana's wide receivers -- Leading receiver Ray Fisher switched to cornerback and Andrew Means bolted early for the NFL draft, leaving sophomores and juniors to handle the pass-catching duties this fall.
Iowa's defensive tackles -- Mitch King and Matt Kroul locked down the starting interior line spots for the last four years, and their backups didn't have many opportunities to develop in games.
Michigan's quarterbacks -- Nick Sheridan started four games last fall, but once again the most important position on the field will be one of the greenest for Michigan, as two true freshmen (Tate Forcier and Denard Robinson) vie for the starting job.
Michigan State's running backs -- National carries leader Javon Ringer is gone, and it's likely that a redshirt sophomore (Andre Anderson, Ashton Leggett) or a true freshman (Edwin Baker, Larry Caper) will take his place in the backfield.
Minnesota's running backs -- The Gophers return practically everyone but remain young and unproven after finishing last in the Big Ten in rushing offense (103.8 ypg) last fall.
Northwestern's wide receivers -- Three starters graduate and junior Andrew Brewer hasn't quite settled in at wideout after switching from quarterback, so there are some legit questions here.
Ohio State's offensive line -- Don't be shocked if Ohio State enters 2009 with three sophomores (Mike Brewster, Mike Adams, J.B. Shugarts) and a transfer (Justin Boren) on its starting line.
Penn State's defensive ends -- Jerome Hayes should be back from another knee injury, but Penn State will be on the lookout for a proven pass rusher after losing Aaron Maybin, Maurice Evans and Josh Gaines.
Purdue's wide receivers -- New coach Danny Hope made wide receiver a peak priority in his first recruiting class after losing Greg Orton and Desmond Tardy, who combined for 136 receptions and 1,596 yards last year.
Wisconsin's defensive line -- The Badgers lose three multiyear starters (Matt Shaughnessy, Mike Newkirk and Jason Chapman) and don't return many proven players aside from ends O'Brien Schofield and Dan Moore.