size does not = strength, though they do have a positive correlation
That's 100% correct. Wow, you have big, dumb muscles? Fantastic. How's the nervous system? Real, hardcore strength gains are neural, not necessarly a huge change in the muscle fiber cross sectional area (size). It's not so much how many you have, but how you get them (recruitment) and type (fast twitch, intermediate, bla bla).
I'm 204 on a good day, but don't life huge amounts of weight by laying in my back and pushing something up toward the ceiling tiles. Boring and largely unproductive. I still do it, but always switch to something far more demanding on my system like putting my feet flat on a wall and doing push ups with 3 fingers.
So, as such I can and do out-lift other bigger guys in the gym. Not bragin, just sayin. I matters most
how and
why, not
what. Can you stand and balance on your left leg, reach down and grab a 90# dumbbell w/ your left arm and snatch it over your head? Fun times.
Protein in muscle building is necessary, but highly highly overrated. Look at the quality and nature (is it DEnatured?) of it, firstly. Makes all the difference in the world. Garbage in, garbage out.