What you mean 4-3-3? 4 flat back - 3 MC - 3 ST?
Is not effective this year under current ME; IMHO.
AI managers tend to use 4-2-3-1 when you are weak and 5-4-1 flat when you are strong.
Any 4231 advice then?
niceIf you are using 4-2-3-1 and you are weaker side; against 4-2-3-1 can exploit it you easily. During the match AI make changes (roles, duties etc).