Why Wasn't Dan Reeves Inducted Into the Pro Football Hall of Fame?

Former NFL player and coach Dan Reeves passed away today of complications of dementia. He would have turned 78 on January 19th. 

After playing for 8 seasons with the Dallas Cowboys and appearing in two Super Bowls while earning one, Reeves became an assistant coach with the team appearing in three more Super Bowls while earning yet another ring.

In 1981, Reeves became the head coach of the Denver Broncos and brought John Elway to the team. Over 12 seasons, Reeves guided the team to three AFC titles but was unable to win the Super Bowl. After a four year stint with the New York Giants during which they made a single post-season appearance, Reeves would become the head coach of the Atlanta Falcons and guide the team to an NFC title in 1998 only to lose to Elway and the Broncos in the Super Bowl. Reeves would remain the Falcons' head coach until 2003 finishing with an all-time record of 190-165.

So why wasn't Reeves inducted into the Pro Football Hall of Fame as a coach? Had he won a single Super Bowl would it have made the difference? Is that all which is keeping him out?

Of course, it would have been nice had Reeves been honored while he was still alive, but perhaps a posthumous induction would bring a small measure of comfort to his family. R.I.P.