Sabres center Mikhail Grigorenko was back in Buffalo on Wednesday after the NHL blocked the team's attempt to send the rookie to the minors on a two-week conditioning assignment. In reaching its decision, the league cited its agreement with the Canadian Hockey League preventing teams from assigning players with junior eligibility to the American Hockey League. ''We determined that the assignment would not have been consistent with our obligations under the league's agreement with the CHL,'' NHL spokesman Frank Brown wrote in an email to The Associated Press. Interim coach Ted Nolan accepted the league's ruling, which came a day after the Sabres demoted Grigorenko to their AHL affiliate in Rochester N.Y., for conditioning. More...