Our full backs are defensively sound, Sagna has improved his delivery too but on the whole neither him nor Gibbs do much. They're not bad full-backs but not great either, and Sagna is probably off anyway.
At the very least, we need a mobile striker, not a lump, someone who will get on the end of chances. Remy is the very least I'd expect, but we need someone on Balotelli or Diego Costa level (I highly doubt we'll get anyone like that).
Flamini is great but he is a walking yellow card. He is a good bench option for the next couple of seasons. Arteta is horrible and really needs to go, his lack of pace is destroying him really defensively, and all his attacking output from 11/12 has disappeared, plus he's more sideways than ever with his passing.
Ramsey is a great midfielder, we need someone to partner him and it's clear Wilshere isn't it, we need someone who will offer more of a B2B role who can do defensive work and go forward, like Gundogan, or simply a defensive shield like William Carvalho, which is what I prefer. Our defence has been great this season (other than those three games where we conceded a lot of goals, we've conceded less than 20), someone like William Carvalho would take it up another level and we'd never concede 6 with a guy like him.
But being realistic, we are only six points off the top, Ramsey and Walcott easily would've kept us in the mix. The big mistake we made is not strengthening in January when we knew both would be out for long periods. We'll easily challenge next season like this season without a great deal of improvement, with a midfielder and a striker we'd actually have a great chance of winning it depending on how the other teams do in the summer.