They stop hemorraging goals on the special units! PK, PP and defending 6v5. Habs 5v5 differential was -4 last year, but their total differential was -53.
At EV, their differential was -9 (170 vs 179). A bit disingenuous leaving out 4v4 and 3v3.
They had -8 with their goalie pulled (4v12), which is a high risk situation for getting scored on. And 6v5 is not special teams as there are 12 players on the ice.
So, -17 with equal players on the ice.
Their true differential on special teams was -36, yet you make it sound like it's -49. This includes -4 for shorties (8v12).
They need to get better everywhere, which is normal for a rebuilding team. They can get better by fixing special teams, but a plus is a plus and a minus is a minus, no matter if it's even strenght or special teams, so if they get better at even strenght, it's still a plus vs their overall differential.
They can be anywhere around -35 in special teams again and get better at EV and be +15 and having less empty net goals, their differential will shrink from -53 to between -25 and -20.
They need to get better at even strenght too, not just special teams.