Because Wright is proving incredibly effective under MM system because he does the simple things extremely well and rarely makes mistakes. He may not have composure in front of goal, he may not have trickery, but he is consistent. Bali has more natural talent but he is not as 100 per cent reliable, he wants to express himself, sometimes it comes off sometimes it doesn't. I was annoyed to see Cissoko go because he is so obviously talented but now I can fully see the MM system in action we can see why. I think Bali is in the same category.
I completely agree with a lot of what you've said, it's amazing to see the resurgance of Wright, who along with me, many had written off as Championship standard.
I think you're particualrly correct around his work rate and consistency, which are hugely important to the effectiveness of MM's system.
The bit where I'd disagree is comparing Cissoko with Mumba. Don't confuse flair with laziness or petulance, both of which I think Cissoko had in abundance, but Mumba doesn't. He has made mistakes, but he has also worked very hard for this club. As fans, we can see that as a full back in a line of 4 often leaves Bali exposed. But higher up the pitch I believe he can be far more effective. As MM's system solidifies itself, we will need to dominate teams who will learn to counter our system. This is where I think Bali's greater ability as a footballer will shine, and I think behind the striker is the spot for him.