The Sabres AHL team needed a new head coach since they promoted their old one to the big club, so they tagged the man whose coaching ability was too much for just one "D".
The Sabres brought in Ron Rolston to run the Amerks because he was a great teacher, a man who made young players better, and because he helped prepare his charges for the NHL.
Well Rolston himself is now in the NHL, and so the Amerks have turned to former assistant coach Chadd Cassidy to run the team in the interim.
Here's a bit on Cassidy from the Amerks press release:
Cassidy becomes the 30th head coach in Amerks history after originally joining the team as an assistant coach on August 31, 2011 and is currently in his second season with the club. The 2011-12 season marked Cassidy’s first in professional hockey after spending the previous five seasons (2006-2011) working alongside current Buffalo Sabres Interim Head Coach Ron Rolston in the same capacity with the U.S. National Under-18 Team. In 2011-12, Cassidy helped guide the Amerks to a 36-26-10-4 record and a berth in the Calder Cup Playoffs.
The team has also named Chris Taylor, former Amerks player and Development Coach, to the role of assistant coach. The Amerks are currently in fourth place in the North Division and ninth in the Western Conference, two points out of a playoff spot.