Sir Alex has to rebuild his Man Utd team. When players like Ronaldo and Tevez leave, rebuilding is probably an appropriate term to use.
He started that process when he signed Wigan's star Antonio Valencia. There have been immediate comparisons to Ronaldo which are natural given the circumstances but the two players have very intrinsic differences.
The Ecuadorian striker is very quick, possesses great ball control, works hard, and can lash a ball from distance. Like Ronaldo, he loves taking on defenders one to one although he lacks some of the Portugese pizazz.
Unlike Ronaldo who could cut in from either flank or operate as the sole striker, Valencia's role is more circumscribed. He operates more like a winger opening the game wide right which limits his versatility.
The greatest departure from Ronaldo however is that Valencia struggles to provide an exclamation point to all the ball possession. Seven goals in 83 Wigan appearances should put to rest Ronaldo like comparisons. At Wigan, Heskey and Amr Zaki as the centerforwards, scored far more goals than Valencia. So he is not going to give the 20+ goals that Sir Alex might be looking to per season. But that is not his strength.
Valencia's greatest gift, the amount of attention he draws when he is on the ball provides an opportunity for Sir Alex to give back Rooney his role as front line striker. Over the years the Everton prodigy who first attracted attention because of his goalscoring exploits has increasingly been marginalized to deeper areas with Ronaldo's output putting everyone else to shade. With Valencia peeling away defenders Rooney and Berbatov could be left open for goal scoring opportunities. This needs to be a tactical decision because Rooney's natural inclination seems to be where the ball is. Which is often times not the best place to be to score goals.
Match practice at Old Trafford will be very interesting this season as a new set of players join and roles get defined or in Rooney's case reclaimed. We should see a spike in his goal scoring tally.