MUCH MIST When he walked away from the NFL at age 30 in 1998, Barry Sanders didn't apologize or explain. He wasn't angry though; after rushing for 15,269 yards, he was just finished with football. And now, after being inducted into the Hall of Fame this year, Sanders, who ranks third in rushing alltime, appears to be finished with his separation from the game. On Thanksgiving, before the Colts beat the Lions 41-9, he took the field with fellow Detroit greats Billy Sims and Lem Barney for a ceremony to retire the number 20 that each player wore. Said Sanders, "It's good to be part of the Lions' family again."