‘Kozak, 22, was scheduled to become a restricted free agent Tuesday. He made his NHL debut Dec. 5 and played 21 games as a rookie for the Sabres, tallying five points (3+2) while averaging 10:29 of ice time. The 5-foot-11 center, whose NHL action was spread across five separate stints on Buffalo’s roster, earned head coach Lindy Ruff’s trust and praise for his reliable, two-way performance on the fourth line.’