I think it's more that it is very hard to sign top players in January. Teams are mid season, likey still on various conpetitions, and our targets have probably made it clear, via agents and their clubs, that they are unwilling to do business in January. My fear would be more that this stance from clubs can change when cash is flashed, and others may view the need as more pressing than us, and beat us to the top targets.
Signing backups is not the way we want to go, quality wise and also the fact that pep knows an unresearched addition can easily unbalance a team spirit.
For the Fernandinho position we must have someone specific in mind otherwise we'd have moved for cover before now. We've seen recently how key this position is, having the physical attributes alongside the mentality to read the game, whilst not getting sucked into the DM mould for whole games, as this is useless to us in a match where we are having 75% possession.
Left back is a little more complicated, in theory we have five first team players who can play there, but only one is a natural left back. I expect Zinchenko, Delph and Danilo's futures need addressing before we make a decision there, and again we'd be looking at only top quality, or the potential to be top quality. Fast, attacking, great passer, strong, cool under pressure, that is only a handful of potential incomings anyway, and anyone doing that well right now is undoubtedly turning heads already in Europe.
I'd expect us therefore to wait until summer. But then expect us to have reserved around 100m for these two positions and no deals early, with maybe another 50m for a younger player also, or bank the balance knowing we need a Sergio and Dave replacement soon too. The wildcard could be if someone else of sufficient reputation moves for our primary targets in January, have we got enough room to move too and would we?