I'm not convinced it's imperative to have a left and right footer in central defence, I do think in terms of a natural body shape to tackle, block and pass it makes sense. It's more strange that if we go for Torres that he will be the second left footed CB we've bought as "completion" for Ming's who as an outsider (villa fan) has been one of our best players.
Either a change in system / combination or the management don't fancy him....