I think we played against Stoke with that midfield, with Pilks, Snoddy and RvW ahead of them, and it worked brilliantly. If we'd been able to play like that consistently we'd have been fine. Unfortunately Johnson as a more limited DM wasn't able to replace Tettey in that system, and Fer had to sit deeper. Then we had even more injuries and it really went to pot.
At least this season I feel we've a formation that doesn't hinge on key midfielders. Mulumbu can cover Tettey, Brady for Johnson, Dorrans and Howson, etc.
That said, an injury to Bassong, Redmond or Jerome could cause us difficulties.