first of all, we don't need any "creative" CMs. vieira-petit and vieira-gilberto had zero playmakers, but they were efficient passers and smart players who created the foundation upon which our front four could attack, and later, ashley cole could overlap on that devastating left side.
but, if this is part of plan to move song further up the pitch, then wenger's truly lost the plot. song might have a good number of assists, but he's a very inefficient passer, a bad presser and offers little leadership or nous from a very important place on the pitch. to me, song needs to sit alongside m'vila or goto the bench.
lastly, there's no reason for this deal to preclude another attacking signing. with the expected departures from the team this summer, we've only just about had a net transfer spend now, and likewise for wages (including whatever's earmarked for van persie).
if m'vila is what i hope he is (crisp passer, good leadership and character, something in between vieira and gilberto in style), then i think it's a terrific signing.