Even before the Montreal Canadiens lost Alexander Radulov in free agency to the Dallas Stars they had a need to add some offensive firepower to their lineup. They attempted to do that by acquiring Jonathan Drouin from the Tampa Bay Lightning in exchange for top defense prospect Mikhail Sergachev, and then taking a chance on veteran free agent forward Ales Hemsky on a one-year, $1 million contract. Both Drouin and Hemsky opened camp this week skating on the team’s top line alongside Max Pacioretty, via the Montreal Gazette. It is a very interesting combination because it involves Drouin playing center, an experiment the team wants to try in its quest to find a top-line center, and Hemsky getting an opportunity to rediscover his offensive game. Hemsky, entering his age 34 season, has always been a skilled, gifted playmaker and a better all-around player than he has sometimes been given credit for being. But injuries, as well as the usual regression for players in their 30s, have taken away a lot of that offense in recent seasons.