Kuz is definitely the x-factor this year, but I'd like to see Backstrom take a step forward in the playoffs because he's seemed relatively ineffective for a few years now come postseason.
I also think people tend to focus on Orlov's mistakes and miss the big picture: he's really good at driving play and scoring. He's been the best Capitals possession defenseman this season and in 2013-14 (of course he missed all of last season) and he gives up only 43 shot attempts against/60 minutes of play this season, by far the best on the team. It would be absolutely crazy to replace Orlov in the lineup by anyone acquired at the trade deadline just because he makes a few risky plays.
Orlov should be seeing top 4 minutes in my eyes the way he's been playing and it's not even close. Orlov scores 1.23 points/60 even strength, second only behind Carlson's 1.25 points/60. You can't just overlook the big picture because you remember he turned the puck over once or twice and it led to a goal against. For every mistake he makes he makes several good plays that lead to extended zone time, shots for, and goals for. He also doesn't get the benefit of much PP time so his point totals aren't inflated by that. Dude is a stud.