Shoulder Impingement / Instability

[jdghost]

Not sure if I'm overthinking this, but this question is reference to correcting impingement by strengthing the upward rotators of the scapula:

Background: I was diagnosed via an MRI with subacromial bursitis. This all started when I was bench pressing and felt pain in my scapula area. after that taking off a shirt and reach down across my body cause significant bursitis pain. The bursitis is mostly gone but I still feel like my scapula isn't working.
My solution to this is to follow the plan on strengthening my upward rotators. However, before i do this I wanted to know if it's possible to have the opposite problem: Strong upward rotators and weak downward rotators? I am strong in pushups (which I do a lot) , strong at pullups, but very weak at things like bent over rows and rear delt lateral machine.
I am also strong at lat pulldowns, but weak if I have to strictly pull the bar all the way to my chest with no bouncing.

I guess what I am getting at is it seems that my rhomboids are weak and since I do alot of pushups my serratus should be strong? Also does it say anything that reach down across my body would cause impingement?