The thing is, if we play 4-2-3-1, we'd have about £40m of center mid talent on the bench haI think we'll play 4231 in most games, and when we do Siggy will play if he's fit. In some games he may decide to go 433 and Siggy will be a bench option. Think as we add more quality players to the squad you'll see Silva make more use of it.
It would be nice to have an extra quality midfielder in the squad but I do think we have more pressing area's that need sorting first, such as RW, CD and possibly RB.
Spurs have shown how having good depth there though is critical, just our luck that we may need schneiderlin to start v Palace.