Our 4-3-3 havent worked becouse we havent had the material to use it.
It relied on Xavi-Iniesta-Busquetes but as Xavi grew older, so did the system become weaker.
And when Xavi left, and an aging Iniesta, it has basicly collapsed.
You need a surtain type of midfield for it to work at our level of play.
A DM, a creative CM and a ballcontrolling AM.
Sorry for a late reply.
Imo, you are basically implying that 433 can work only with a perfect set of midfielders like Xavi-Iniesta-Busi, plus Messi in attack to save our asses.
Even then, if 433 can work only with perfect midfielders, is that formation really THAT good?
Either way, we won't have a new Xavi and Iniesta soon.
And soon we won't have Messi and Busi either.
So, imo, we have two options:
1. Stick to 433 and play poor man's version of it like in the last season
2. Move to a different formation, more suitable for our starters, who will probably NEVER again be of Xavi-Iniesta-Busi level
People mention over and over how our midfield sucks etc.
Ofc, it could be improved.
But we played 110 years without Xavi-Iniesta, then 10 years with Xavi-Iniesta and now we will play again for 100+ years without Xavi-Iniesta quality.
Again, instead of trying to replicate Xavi-Iniesta era, we should wake up and move forward.
So, the question is:
Can 433 work with average set of starters and midfielders?
Without a once in a lifetime world class Rb?
With Messi drifting to middle?
Without Pep?
Without a plan b etc?
. It will help Aurier deal with his impulses and stupid 
