Going on the assumption that Mazacar is the starting option for the attacking band, we still have Victor Moses, KDB (his natural position is winger/amc) and Marin on the bench. I'm perfectly comfortable about that in both senses: both the strength of the starting players as well as the amount and quality of the depth players. I dont think any team in the league has better starting quality or depth in the attacking band. If anything, the attacking band is the last place we need to strengthen.
I think its pretty obvious to everyone that a centre mid is WAY more needed. If not centre mid, good arguments can be made in favour of getting a world class center back, or a world class centre forward.
On the other hands, i think the last thing this team needs is another winger who can 'sort of' play striker (pretty sure that's what Victor Moses was for). I understand Schurrle has been very impressive and offers a more direct outlet (as well as apparently more hardworking), but once again, that's what we have Victor Moses for. I dont really think there is room for him, not if KDB comes...having KDB Schurrle and Moses on the bench sounds awesome, but its a waste imo when there are other areas we have been very weak at.