The only possible formation we can field with 3 defenders and decent defensive coverage, is a 3-5-2 with two advanced and spacey fullbacks (Grossa/DC, Caceres/Salih) playing at the same line with two DMs.
Considering our lack of offensive options, atm though, it could be as well be a 3-6-1, or a 3-4-2-1. So dont be surprised if you see any of these formations.
We dont have quality material at the defense and we have an abundance of midfielders, so we have the material to support these formations.
As for their effectiveness. We are not going to fly high anyway, our season is already wasted, all we need is to start winning the odd games.
This formation are largely considered risky, but if they are combined with a proper tactical plan, they can be more effective that our current... status...