Obviously you can play him where you want, there are no rules, play with 5 strikers, attakers positioned on the corner flags, your choice, granted I do not agree with this style of play, but the choice will always be yours....I am said to say.
Balls to play carlos up front, I guess I would take balls, to play carlos up front and drop ronaldo, adriano, or even ronaldhino to left back. he plays left back because he plays that position exceptionally well and has done for a decade, plus for both club and country there are quality forwards, so why would you even consider it. Hopefully in future releases of WE or PES kanomi put pave to this type of random positioning.
Before you even think about replying to this, my opinion, if you have never played the game at any decent level don't bother, because you probably think that a player will do well in any position (real life), maybe on a sunday morning, and as there are no sunday league teams in either pes or we or dont believe the makers intended it to be played this way, reinforced by the simple fact they give players positions within the game.
but as I said play them where you like, your choice!!!