I totally buy it.
My dad will be 58 this June and I can outlift him on anything in the gym. HOWEVER, when we box, wrestle or jus goof around, he kicks my ass. And it's not from my lack of trying. I think that it is one thing to be stronger on a trained exerise through a prescribed range of motion, and that's all well and good. A life of hard physical labor, I think, gives a person another kind of strength. He grew up in the country and has done hard physical labor all his life.
I have too, but to a lesser degree. I have friends that can out-lift me, but years of splitting wood, throwing hay, and other outdoor labor shifts the odds a little.