Luton is up there too, they have risen about the same amount of places as we have, so too Sheffield United, I know they were just relegated but they were in League 1 when DS joined Villa.
I know DS is doing a good job but there is no denying that we have has massive investment in the squad. This, without doubt, makes improvement easier than if the investment wasn't made. With the money invested it is fully expected that Villa would be a PL team and if we were currently in the Championship I would expect that DS would no longer be our head coach. In the last few seasons DS has shown in games the inability to have a plan B and last season the inability to come from behind in a game. We can see these weaknesses and fans think that perhaps a different manager would not make these mistakes. But as mentioned, DS is still learning, he is new to this so it is expected that he will make mistakes. The key is that he develops as a head coach as a result of these experiences and this will help improve our performances. I do understand the perspective of fans that believe we could have improved more with a different manager.