I thought it would be interesting to come up with the list of players for whom a system with back 3 is arguably more suitable than back 4 as well as the reverse and from that try to judge whether our squad is better set up for one or the other system. I have no idea at the start which list will be longer. Let's go!
=======
Better with a back 3:
Sakho – based on the evidence so far, clearly much better there
Skrtel – it's a close call, he's been part of decent back fours in the past too. But I think playing in the middle of a back 3 suits him especially well
Moreno – he would have been a defensive liability in a back 4, but with Sakho behind him he's fine
Markovic – unlikely to get much game time playing in the front 3 at the moment, he definitely benefited from the introduction of the wing-back position
Ibe – same as Markovic essentially
Can (for now) – it's a fact that he found steady game time only after the switch to the back 3. However his versatility and quality means in the future he can adapt to any system.
Better with a back 4:
Johnson – not enough speed and stamina for wing-back role any more, not good enough of a defender for CB
Enrique – not enough pace for a wing-back
Manquillo – it's not a coincidence he stopped playing after we switched systems
Flanagan – another defensively oriented FB who will struggle to find a place for himself in 3-4-3
Allen – a close call, but with 3 CBs there is one less place for a midfielder and he is the most likely one to miss out when everyone's healthy
Unclear/doesn't matter:
Lovren
Toure
Gerrard
Lucas
etc.
=========
So far six players for 3-4-3, five for 4-3-3. But look at the names – all the big talent, promise and investment is in the first group, whereas in the second group probably no one is going to play a big part or any part in the team next season. So I think it's fairly clear that 3-4-3 will be our system for the foreseeable future. The nice thing about it, apart from the added defensive solidity, is that it allows Rodgers to field two young hard-working coachable attacking players – his favorite type – in wing-back positions and not worry that it's going to cost us on defense (as it would if those players were asked to play FB) or decrease our effectiveness in attack (if they had to occupy one of the attacking midfield places).
It's really simple and foolproof and great for developing attacking talent. Those who "graduate" the wing-back school will one day get promoted to the "core" group of attacking or central midfielders and join the likes of Sterling, Coutinho and Henderson. There is simply no other system that would allow Rodgers to squeeze Markovic, Ibe, Coutinho, Sterling and Lallana – 5 young attacking midfielders! – all in the same lineup and still have a team that is defensively solid and not too lightweight. So we can be like Arsenal with an overabundance of AMs in every position, but thanks to the 3 CBs also a bit more steel and power at the back.