He just looks a lad who wouldn't cut it in the PL. I remember likening him to Jelavic & Soldado who in slower/more technical leagues were good, but in the PL struggled. He remains a really good finisher, but the issue is being able to get on the end of chances and having a team set up to make him lots of opportunities.
I am also toying with the idea that actually finishing ability isn't always what differentiates top strikers, but their ability to allow others to make them chances. If you take Lukaku, he does miss chances but he gets plenty each game. The size, power and physique of the guy means for a midfield player it must be quite easy to make him chances. You put the ball into space and he is on the end of it.
Tosun works hard and I imagine Allardyce could have got a tune out of him. However I'm unconvinced anyone of his physique and lack of pace has much of a chance in the PL.