All shot differential with no goals tells me is that they have the right system and the wrong personnel up front - something which you don't need numbers to tell you anyway. They don't currently have a 30-goal scorer in the lineup. They barely have three 20-goal scorers (Elias, Clarkson, Henrique) and at this point all of them - even Elias - are complementary players. Can't trust Zajac to get 20-25 anymore now that he's been awful two straight years without Zach. Half the other forwards don't even have double-digit goal potential. No defenseman currently has 10-goal potential either.
Even with Kovy they need a 'bit' more scoring at all positions. There's a reason Kovy was playing 26 minutes a game before he got hurt and that can't continue.
Kovalchuk's ice time was actually going down when he got hurt. DeBoer was giving him more 22 minute games. I'm not that concerned about this as long as they stop double shifting him at even strength, which they didn't have to do - that was something they chose to do.