I'm not so sure about that but
His 34.3kmh skate up the ice to that goal while carrying a puck (which slows one down some) is currently 7th on the Leafs this season. Everyone's times are slower at the start of the season on NHL edge. That will probably change when the OT skating gets added tonight. It is not amazing or breathtaking and won't even be average by the end of the season. But I'm not ready to declare him a slug yet because I've seen it a few times this season.
He was only 94% in the faceoff dot. It helps if you don't have to face Claude Giroux 6 times (who is probably 2nd or close to it to Bergeron in faceoffs over the last number of years).