There are some suggestions that we are playing with 3 at the back against Burnley as well. Brendan experimented with that formation a couple of times last season (without much success I seem to remember) but it does seem to be coming back into vogue again, Van Gaal for instance used it at the World Cup (and against us in pre season) with some success.
In theory it might suit us, 3 at the back allows you to flood the midfield and to fit more attacking players into your starting XI.
We are at our most effective playing a 4-3-3 but when you consider our current attacking options (Sturridge, Markovic, Sterling, Lallana, Coutinho, Ibe, Lambert) picking just 3 of those will leave a lot of talent on the bench.
Another reason why 3 at the back might suit us is that we have a lot of CB's who can pass the ball well, a lot of teams are put off playing that style because their defenders aren't comfortable on the ball but we don't have that problem.
It would be a lot easier to carry Gerrard playing with 3 at the back as well because with more numbers in and around the midfield area he wouldn't be so exposed and It would suit Agger too.
It might be worth thinking about.
Here's an attacking version of the 3 at the back that we could play against some of the lesser lights of the division at home, it allows us to get Sturridge, Sterling, Markovic, Lallana and Coutinho in the team at the same time, obviously away from home you could flood the midfield with the likes of Can and Allen etc.
Mingolet
Sakho/Skrtel Lovren Agger
Gerrard Hendo
Sterling Lallana Markovic
Coutinho
Sturridge