This may further explain why the Broncos drafted Knowshon Moreno. The Broncos released J.J. Arrington on Wednesday after it was determined the running back will need season-ending microfracture surgery on his troublesome right knee. Arrington, who was slated to become the Broncos' third-down back after he was signed away from the NFC champion Arizona Cardinals, had been trying to recover from offseason arthroscopic knee surgery performed by an Arizona surgeon. As Arrington struggled to regain strength in his knee, the Broncos used the No. 12 pick last month to select Moreno, a running back from the University of Georgia. Arrington will go down as the tailback the Broncos once badly wanted but never had. On Feb. 27, the opening of free agency, the Broncos and Arrington reached an agreement in principle on a four-year, $10 million contract that included a $3 million guarantee in signing bonus and salary. http://www.denverpost.com/broncos/ci_12461192 I wonder if he already has his plane ticket to Houston yet.