I remember this one kid in school. Never lifted but was strong. Real strong. One time he went to the gym and we thought he would have high numbers in the gym. He just had modest numbers. Nothing great but for whatever reason he was still strong. Like he beat you in arm wrestling or if he wrestle you he could take you down and hold you down. He was not a wrestler by the way but had strong core and was hard to move.
At the flip side I met guys who lift all the time with decent weight numbers. But when it came to do functional stuff they were like average.
What exactly do you mean by functional? Picking heavy things up off the ground is about as functional as you can get.