You just showed you dont know much or anything about the teams you're talking about. Let me break down every bit for you.
- Lo Celso + Lucas (why Lucas do not plays? WTF) - Lo Celso plays in the middle and is an Eriksen replacement and has played decent in his first start vs Sheffield, what does this have to do with Lucas who is a forward/wide forward?
but my dream is just make a 3-4-3 with Eriksen and D.Alli going to attack (the LB and RB actual is too bad) Lucas and Son can back for help! - Eriksen isn't interested, he not played well in the last 8 months, why should we play him when he's not playing well, he's had so many chances. His heart has gone from the club, better to start fresh without him. LB is OK, RB needs fixing, you can't reply on Lucas/Son to defend, that's what the L/R midfielders are for, and Lucas/Son will help only if 100% needed.
- Gazzaniga ofc they can buy someone better - he's decent, not a bad replacement at all, single-handedly stopped us losing 10-1 vs liverpool.
+ defenders - a monkey could have worked this out.