this depends on oppo's quality and oppo's tactic

4-5-1v can be used for defensive and attacking formation as well.
So you should make your tactics counter your oppo's one.

But I am using this formation as well I can tell you that it is not unbeatable.
But it has many advantages:
1. Wing AMs which rule the game this time period
2. DMC which will help in oppo's long passes, and will give support to defense and middle midfielders.
3. 4 defenders covering most attacking formations.

TIP: I do not use 4-5-1v against formations attacking through the middle