Well, Puyol was playing when we lost 2-0 at the San Siro and lost 3-1 to RM. Masch was playing when we beat Milan 4-0 at Camp Nou (and did quite well besides that chance he gifted Niang). Neither should be starters any more though, Puyol is old, injury-prone, slow (which Pique is as well, which is part of the reason we've been so vulnerable to counter-attacks) and not what he used to be (still a great defender for someone so old though, and could be a great 3rd choice CB next season) and Masch is not a real CB. Which is why we need a new CB.
And IMO, the reason our level of play increased drastically after Puyol returned is because Pique returned as well. With those 2 missing and Masch off-form (and showing he's not a real CB), our defense was absolute shit. After those 2 came back, we had a semi-decent defense, at least. Like I said though, the Pique-Puyol pairing has its problems (both are slow, Puyol is old and not what he used to be, etc), as we saw in the 2-0 loss to Milan, the 3-1 loss to RM, etc.