Sorry but Bony has only been missing for one game so far, so as of now you can't compare. Michu and siggy are no comparison, if you where to select a team with last years players and this years it would look like this:
Fab (Vorm)
Rangel, Fab (Chico) Ash Taylor (Davies) Defence
Leon, Ki (Canas)
Dyer, Siggy (JDG), Monterro (Hernandez)
Bony/Gomis, (Michu)
so:
Ki (Canas) CM/CDM
Monterro (Hernandez) RW
Siggy (JDG) CAM
Gomis, (Michu) ST
Don't agree with that, JDG never really played for us in the AM role, he always found himself further back.
Last season, our ideal starting line up for me personally was
Vorm
Rangel - Chico - Ash - Davies
Britton - JDG
Dyer - Hernandez - Routledge
Bony
Pablo always did better in the middle than he did outwide due to his style, I always felt he was one of our better players, granted his first touch let him down at times, as did his short passing, but as a player who could create chances, there was no better in our team IMO.
You also list Michu as our first choice striker under ML, or are you forgetting that Bony was our top scorer last season too? A few times he tried playing Bony up front with Michu behind in his preferred position, but due to injuries and fitness issues, they never really got the chance to gel, which for me, was our bad luck as I think they would have been a force to reckon with, such as the link up play between Siggy and Bony this season. I think Michu/Bony would have been a better combo.
As for comparisons to this. For me:
Vorm -> Fab = There is no doubting that Vorm was a good keeper, and I was disappointed when Fab came, but he has proved me wrong, and I do love that he is good in the air. A step up, but not a great deal in it, as Vorm was much a better distributor of the ball which would help us open the pitch up.
Chico -> Fernandez = Chico for me, we have gone downwards IMO, as much as Chico could be a loose cannon, and his rolling was annoying, he was a cracking CB who would get in the faces of the opposition, we don't have that now IMO, a player willing to unsettle the strikers like Chico could.
Davies -> Taylor = Davies, however Taylor is still one of my personal favourites and am really looking forward to see him keep growing.
JDG -> Ki = I was never JDG's biggest fan, but then thats because I never liked him in this role, preferred him further up the pitch. Ki however has been our best player this season for me. So Ki wins this hands down for me. The scary thing is, out of Ki and JDG in that role at first, JDG was better. And he was only getting better in fairness. This a Ki/JDG pairing would have worked well for us this season.
Hernandez -> Siggy = Siggy, and its only just, and primarily to do with the injury time Pablo had, I find both players suited the role, but Pablo never really managed to get a solid run in the team as injury hampered him, and he always took a few games to get back into the swing of things. By which time he would get injured again. There was a reason why even through injury, many liked Pablo, because they could see his potential, we just never really got chance to enjoy it for long enough.