Don't know anything about Sergachev. How does he compare to Drouin?
Serg has the chance to be a legitimately elite Top Pairing LD. He was a huge cornerstone piece for the Habs future seeing how weak we are on that side of the back end, but apparently Beaulieu is sticking around and the Habs need the offensive spark from J.D.
You're getting a guy who will play Top 4 for the next 10 years for Tampa Bay. I don't personally understand the trade, but I guess with how heavy stacked your offense already is, taking a hit on this trade to get a solid defensive player is a good look. I expect this means Johnson and/or Palat return to Tampa next year, though.