Well, I saw them a few times and my conclusion was that in possession they played a 3421 with high wing-backs, two midfield pivots and two fantasistas looking to pick up space between the lines. Often they would form a box formation with the pivots. They aren't needed to drift wide much because the wing-backs are very high.
The interesting thing is that in defensive formation, the back 3 drifts to the right so that the right centre back becomes a full back and the left wing back drops into the back line. In other words, they defended with a back 4. The left fantasista moves to a traditional left-midfield role. So, defensively, it's a 4411.