It isn't just Foles. We need an entire new offense. Other than Gurley and Austin, nobody else on that side of the ball for the Rams is NFL worthy.
On offense, I think our line will be ok IF they can stay healthy and we can get some continuity there. Lack of continuity on OL hurts, and it hurts even more when you have a lot of rookies. Next year all of the rookies will be veterans, and thanks to injuries this year, they will all have received some playing time. That being said, would have been nice to have more veteran presence there this year.
Where we need help the most is at QB, because it's clear that Foles isn't the answer to anything and Keenum is at best a stopgap. Next, we need some WR's, because Quick seems to have lost his confidence after his injury last year, Bailey's future is clearly up in the air, while Welker and Britt are not likely to be long term contributors here, particularly the former.