all brawn and no brains

all brawn and no brains (big and strong and muscular but not very intelligent) — физически сильный, но умом не блещет
be all brawn and no brains (to be physically strong but not very intelligent)
≈ сила есть — ума не надо

Example 1: I agree he's got a good body, but he's all brawn and no brains. (Cambridge Idioms Dictionary)
Example 2: College girls like to date football players, but the problem is that athletes are sometimes all brawn and no brain. (David Holmes)
Example 3: Arnold looks like he is all brawn and no brain, but, actually, he is pretty smart. (David Holmes)
Example 4: It is a form of sexual discrimination to say that big, strong men are all brawn and no brain. (David Holmes)

Why every girl who just talks to him is automatically assumed to put out, and if she doesn't she is marked for life either way it goes! I beg you Siph, don't go out with that beefcake! He's all brawn and no brain anyway! (Ola Vay. Georgia Peaches: A Novel Extraordinaire. iUniverse. 2001)

Donalson was all brawn and no brain. He was a footballer at the Academy, and a good one we'd heard, and that, no doubt, was what got him through, because, for intelligence and common sense, he was null. (John Long. Johnny Barleycorn. Virtualbookworm Publishing, 2012)

Any study of the Olympics forces one to discard one of the world's most cherished stereotypes, that of the dumb athlete— all brawn and no brain. (The Rotarian an international magazine. – Jun 1976)