They have three superstar forwards in Ovechkin, Backstrom and Kuznetsov.
They have Oshie, Williams and Eller as reliable vets. They have Burakovsky. and Johanson as enigmatic wildcards.
They have three x top pairing defenseman (Orlov, Niskanen, Carlsson) and they have excellent depth in Winnik, Beagle, Azner and Wilson.
Braydon Holtby is one of, if not the actual best goalie(s) in the NHL.
So what do they even need?
Their GM spoke recently about maybe adding nothing. He talked about how Lars Eller took twenty or so games to really find his role on the new team, and wondered out lout whether or not it was worth disrupting the chemistry for a slight upgrade.
Add in the fact that, generally speaking, the players available at trade deadline day are usually past-their-prime ex-stars looking for one last kick at the can (Iginla, Doan) and you can make a case that the Capitals should do nothing.
That being said, most GMs don't have the balls to stand pat when a chance to improve their team comes along.
MacLellen can say what he wants, but at the end of the day, it is highly likely that he adds something.
Personally, I would pass on both Doan and Iginla. The last thing you want to do is bring in guys who you can't healthy scratch, and who are slow. Neither one of those guys is helping the Caps.
If the Caps want to be conservative, one player to target is Radim Vrbata - he can score and he would fit in nicely on the second line.
Martin Hanzal is another target - he's so big, and when he's healthy he's essentially a lower-case first-line centre. If he was added then the Caps could run Backstrom-Kuznetsov-Hanzal-Eller down the middle and have by far the best four-centre group in the NHL.
Other than that, all they really need is a third-pairing guy. If they could add to their already deep defense with a top-four capable guy for their bottom pairing, I think they could be unstoppable.
To sum up: a scoring winger, a defenseman, maybe a centre to create incredible depth. The Capitals don't need anything - but they do need to go deep in the Playoffs.
That is if they want to be fairly conservative.
The Capitals are at the point where they need to win a championship however, so being conservative may not be an option.
Maybe the Capitals feel that they'll never have a better shot at the cup and they want to copy the Penguins who brought in Kessel and won a Cup.
Adding Matt Duchene to the third line would give them a Pittsburgh-like three-first lines. It would be risky, but maybe the Capitals are at the point where they have no choice but to get a little crazy.
The problem is that as a team that has been good for the better part of a decade, the Capitals don't have many desirable prospects, nor are the draft picks they can trade very high. So who knows how realistic of a possibility this is.
That said, the Penguins were able to offer enough for Phil Kessel, and Phil Kessel is unquestionably a better player than Matt Duchene.
In my opinion, the Caps need to go for it and do something major. I think if they're creative and willing to spend, that they can do it.