Legal or illegal

Hi, I played the last season's
--------ST--------
AML----------AMR
----MC----MC----
-------DMC-------
DC-DC-----DC-DC
--------GK--------

I was 2 seasons undefeated.

Now I want to try
--------ST--------
AML--AMC--AMR
----MC----MC----
-------DMC-------
---DC-DC-DC-----
--------GK--------

Good idea? Bad idea?
I played already 3 rounds against friends and won almost 3:0.
I played offensive.
I had 60+ ball.

Well if you tried it and get 60% possession then it definitely isn't illegal. I have used this formation myself and it isn't that amazing to be honest...

your flanks could get owned if you're not careful.