20. Danny Manning
Since tearing his ACL in his rookie season and receiving arthroscopic surgery to repair the damage, Manning was plagued with knee issues for his entire pro career. His potential shown in college was never realized. Manning was named the Most Outstanding Player in the Final Four and Player of the Year in 1988. He also led the University of Kansas to the Final Four in 1986, before winning it all in 1988. Manning left KU as the all-time leading scorer with over 2,500 points before turning pro in ’88. Manning’s play began to pick up as his knees got healthier, posting averages of 20 points or better for the 1992-1994 seasons, garnering All-Star selections for the ’93 and ’94 seasons. Things were starting to look up for the KU product, but his ailing knees required two more surgeries that prevented him from becoming the player he was expected to be before retiring in 2003. As a big time KU fan, this one still hurts to this day. This man could have been great.