Baltimore Colts Hall of Fame tight end John Mackey on the bench in undated image. (National Football League)

A Sept. l8,1969 photo of John Mackey of the Baltimore Colts. (Associated Press)

End John Mackey of the Baltimore Clots takes a first half Johnny Unitas pass good for a first down to the Ram?s 40-yard line as Maxie Baughan (55) moves in to try to break it up. Tom Matte (41) of the Colts is at right on Dec. 17, 1967 in Los Angeles. (Associated Press)

Green Bay quarterback Bart Starr #15 and Baltimore Colts tight end John Mackey #88 of the West watches from the sideline against the East in the 1967 NFL Pro Bowl at the Los Angeles Memorial Coliseum on January 22, 1967 in Los Angeles, California. The East defeated the West 20-10. (National Football League)

This Nov. 15, 1970 file photo shows Baltimore Colts tight end John Mackey catching a pass from John Unitas for a touchdown as Buffalo Bills defenders John Pitts (48) and linebacker Paul Guidry (59) pursue, in Baltimore. (Associated Press)

Baltimore Colts Hall of Fame tight end John Mackey on the sidelines during a 28-24 win over the Los Angeles Rams at the Los Angeles Coliseum in 1968. (National Football League)

Pro Football Hall of Fame and Baltimore Colts tight end John Mackey (88) watching in frustration in the Colts 16-7 loss to the New York Jets in Super Bowl III on 1/12/1969 at the Orange Bowl in Miami Florida. Super Bowl III - New York Jets vs Baltimore Colts - January 12, 1969 (National Football League)

Baltimore Colts Hall of Fame tight end John Mackey. (National Football League)

This July 20, 1970 file photo showing NFL Players Association president John Mackey, right, talking with New York Giants' Fran Tarkenton, left, and Los Angeles Rams' Roman Gabriel, center, before a news conference to discuss issues between the NFLPA and team owners, in New York. (Associated Press)

Hall of Fame tight end John Mackey of the Baltimore Colts in a 1966 game. (National Football League)

FILE - This Aug. 1992 file photo shows NFL Hall of Famer and former Baltimore Colts football player John Mackey, center, after receiving his Hall of Fame ring, at halftime of an NFL game between the New Orleans Saints and Miami Dolphins, in New Orleans. (AP Photo/Ted Mathias)

This March 22, 2007, file photo shows NFL Hall of Famer John Mackey showing off his Hall of Fame and Super Bowl rings at his Baltimore, Md. home. (AP Photo/ Steve Ruark)

John Riggins, Al Davis, John Mackey, and Lem Barney are introduced as the Pro Football Hall of Fame Class of 1992 on the field before the NFC's 21-15 victory over the AFC in the 1992 NFL Pro Bowl played on February 2, 1992 at Aloha Stadium in Honolulu, Ha. (National Football League)

John Mackey poses with his Hall of Fame bust and mural in 1992. (Pro Football Hall of Fame)