Klaus Think you're pretty spot on. At Atalanta he wasn't playing much with his back towards goal. He was running primarily down the left channel as you say. Ten Hag seemed to have thought big strong striker = targetman. And then he had to feed off scraps from the likes of glory hunters like Garnacho and Bruno (and Antony heh). By the time Amorim arrived, his confidence was completely shot.
Denmark plays a very similar system to Amorim actually under newish coach Brian Riemer who initially decided to stick with Højlund despite him being in horrendous form. But Højlund has not managed to improve under Riemer either and based on the last internationals, our old pal Mika Biereth is the new starting striker for Denmark.