That's total and utter rubbish on two counts.
Firstly I think looking at the way the teams were set up he was playing centre mid, or at most attacking midfield in a diamond style formation.
But if what you say is true, then that's, if anything, even more mind boggling. Why on earth would someone switch to 4-3-3 from 4-4-2 in the final 20 minutes of a game against City who have two strong centre midfielders?! Why weaken our midfield when they'd be doing their utmost to break us down in the final 20 minutes? It DID cost us the match, yes you can't say anything 100% but if we had someone with experience of playing in centre midfield there, they would've found some way of distributing that ball out of the danger zone which Rocinha failed to do.
And secondly, both Olsson and Emerton have a lot of experience of playing in the positions they were in last night. Olsson is arguably a better LW than LB, and Emerton is a utility player who has played right wing quite a lot during his career.