Maybe something has changed for you personally?
One of the most important aspects of doing well in a match for me personally has been patience.
Patience for when to commit in a Light, patience to wait for the right moment to push in an Assault, patience for everything else in between.
I find that when I'm stressed, because of work or other reasons, or whenever I'm tired, I tend to regard MWO as a way to blow off steam. Patience goes right out of the window and performance is right on its heels.
I'm much better off picking up the single player campaign of some shooter instead and mindlesly gunning down AI opponents. MWO rewards patient play, not recklesness.
(But stompy robots feel sooo goooooooood for smashing face, some decent AI opponents would be great in this regard, saves me from getting myself wrecked when I just want some stomp-stomp, boom-boom, pew-pew)