The hard-hitting safety, who spent his entire eight-year NFL career with the Bears from 1975-82, explained the origin of the "46" defense last September during an appearance on Bears Roundtable.
"[Ryan] never called anybody by their name," Plank said at the time. "You were either a number or you were an adjective and it usually wasn't a complimentary adjective. So I was a number; I was very thankful. He drew all the numbers on [a chalkboard] and he brought me down from the free safety position and put me right in that middle linebacker position and circled my number three times and said 'we're going to call this the 46 defense.