Tbh with the state this team's in right now I don't think having a mid-tier player or two back will make much difference. To me the biggest problem is they aren't playing as a 5-men unit on the ice as they did last month.
On offence there's too much space between forwards and defense pair, so cycling gets broken up easily letting the other team gets to the loose puck and clears the zone. On defence our gap control is also often suspect, eerily similar to the last year's level sometimes, and the other team skates circles around us at will.
In situations like this it's gotta be the coaching staff who should brainstorm and come up with necessary "adjustments" to their game plan, before each game based on the opponent.
You just can't keep playing the same style of game every night and pray "Good things will happen if we keep doing what we're doing." Other teams study you, video review you and figure out the best way to shut you down, especially when you're a good team.
This is not a knock on Green btw. Rather, it has perhaps more to do with his assistant coaches because usually they are the ones who come up with detailed game plan corresponding to their area of expertise (Brown & Baumer in particular).
You can't sustain winning in this league without constantly adapting and adjusting. It's that simple.