The best athletes to retire in their prime
Patrick Willis Retired in His Prime, But Where is He Now? - FanBuzz
Calvin Johnson continues the trend of NFL stars retiring early
Patrick Willis Is Retiring And That's Just Fine – UPROXX
Patrick Willis Explains Decision to Retire from NFL
49ers news: Why Patrick Willis should be a lock as first ballot Hall of Famer - Niners Nation
Patrick Willis retiring after eight seasons with 49ers
NFL star Chris Borland quits over head injury concerns - CBS News
Might ex-49ers star Patrick Willis come out of retirement?
NFL: Players call it quits in prime of careers
Willis: Maybe it's not all that surprising - Mississippi Sports Hall of Fame
The NFL as it is Known is Not Sustainable - Canal Street Chronicles