I think in theory mate, Mina makes a big difference. Having a lad who leaps and is 6 ft 5 is bound to help any team. In a zonal marking side probably more so as you can't (or shouldn't) be able to run him under the ball.
It's probably a bit more complex though. Our issue is we lose a lot of first balls at the near post and we are ill disciplined when it comes to the 2nd ball. We have a zone outside of our 6 yard box 3-6 yards out completely empty. It is symptomatic of a side that everyone is facing the first ball and not holding their positions well enough.
It's strange as Tosun attacks the ball so well in the opponents area but it is quite a different skill. He's a big lad who's good in the air but seems ill suited to that role. We probably need to find a new player in that position. Possibly Mina could do that. It would be unconventional to have your biggest aerial threat in what is a relatively innocuous zone but that is the root of much of our problems.
Alongside that we do have to do better on 2nd balls though. If you the man who's zone is the back post while it's important you shuffle across you shouldn't go past the centre of the goal really. In doing so, in many ways thats a bigger mistake than Tosun missing the first header. You will sometimes lose headers, but you should have no excuse for not keeping shape. I remember playing fullback and coaches would always say you should never go past the goal and in many ways its the same thing. It's a critical zone and in truth had we have kept men in there it's unlikely we'd have conceded at Bournemouth or Southampton and may well have even stopped the Huddersfield goal.