Proxy is still in a state where she's still just too good at everything, she repairs, defuses, and plants extremely fast due to being a tech, has mines that will instagib you, is extremely fast and puts a LOT of pressure on objectives, as well as being completely ridiculous in a 1v1 or even in a teamfight.
Her ability to get around at such ridiculous speeds coupled with her instakill mines and her 2 shots (sometimes even one shot) shotgun gives her a rather unfair advantage over the rest of the mercs. after the first nerf was implemented for her, things were fine, she was rather toned down and became a much healthier merc, then the moment the fragger vaselli changes hit she began to spiral out of control once again. It would appear vaselli and fragger were what was keeping her in check after the nerfs.
I feel bad for the poorbush whacker players (Not saying bushwhackers bad, he's really good at holding down the fort) as proxy overshadows the choice of bushwhacker completely. She does everything he does (without the turret) and then some.
You rate her combat very low when currently she's one of the most oppressive mercs in the game. Her only drawback is low hp, but the fact that her shotgun practically 2 shots + having massive amounts of speed completely nullifys the weakness.
My suggestion would be to lower her hp down to aura standards or at least cut the speed to a reasonable amount to match how strong the rest of her skill set it.