Rarely lose with CC necrons in 5th ed. I've had people concede at the bottom of turn 2 and 3 against my army. It's just that unfriendly. I've never had that kind of success with my Eldar (or any Eldar build I've fielded).
What BoLS ignores is the high number of high-toughness, save-ignoring, quality armor save units we can put on the table which, when coupled with a reduction to LD7 against the non-fearless sorts, means a whole lot of break tests. Also, against high-power fearless units, Deceiver and Pariahs can force them off the table without even having to engage.
There's absolutely nothing wrong with Necrons in 5th ed that can't be corrected by avoiding unfavorable list builds. Even an all warrior/monlith/scarab list can still function alright, with a few monoliths around. I've seen Necron armadas systematically wreck opponents by applying the right pressure at the right time.
Necrons will suffer if you ignore 5th ed strategy when list building, but if you keep the game mechanics in mind, they should do fine.