What would be your XI? That squad was highly unbalanced.
I'd start the 2010 WC with:
Romero
Zanetti(C)
Demichelis
Samuel
Heinze
Mascherano
Pastore/Cambiasso
Tevez
Messi
Di Maria
Milito
Roughly a 4231:
I'd play with Carlos Tevez as a Number 10/Second striker playing behind/off the Target Man Milito. I trust the mad work rate and pressing ability prime Tevez had. Was an absolute animal.
Double pivot of sorts with Mascherano and Pastore. Mascherano as the anchor and destroyer; Pastore as the technician, recycler, ball carrier with more attacking tendencies.
Messi as the RW with total freedom to roam and zero off the ball responsibilities. Would build the team around him.
ADM will be my Left Winger. Young ADM was rapid, tricky, immense 1 on 1, could beat his man and put in perfect crosses, cutbacks or clever final balls easily.
Milito as the Targetman. Great in the air and very underrated all round game. Great instincts and was very clutch in 2010. People forget how good he was in Inter's treble winning side.
Higuain would be my first choice sub for the Striker role.
Zabaleta in the mix. Cambiasso for Pastore whenever needed.
If up against a stronger team and I need more physicality in midfield, I'd go with Mario Bolatti instead of Pastore.
Maxi Rodriguez will be one of my key bench options too. Baller.
Other bench options like Veron, Gutierrez, Otamendi would be there.
TACTICS:
Basically without analysing opponents, the basic structure of my team would be as follows:
Would play a mid block in the defensive line. Would perfectly suit the experienced warriors Zanetti, Samuel, Heinze..... Also it's a death sentence to play too attacking and naive in international knockout tournaments.
In possession, would play a progressive passing game with technicians like Messi, Pastore, ADM, Mascherano, Tevez taking care of the ball progression and creation of attacking scenarios. 2010 Messi would have so much attention on him that it'd create loads of space for the others. This is why switching the ball from one wing to another will be a deadly prospect. Messi is a cheat code to unlock parked buses/compact low blocks.
This team would be deadly on the break with fast balls into the space for elite counter attackers like ADM, Tevez and Higuain or long balls for Milito to knock down.
Very hardworking team off the ball except Messi. ADM, Tevez, Milito all had elite defensive work rate and pressing capabilities.
Most importantly, this team has the perfect balance of experience and youth, technique and grit. Players like Zanetti, Samuel and Milito were fresh off a treble and the team had amazing leaders with character like Zanetti, Mascherano and Samuel. Had the best player in the world and stacked attacking options.
Great team and would have been very balanced with a good coach and a half decent Federation.