We are sorely lacking in penetration once again. The only players running in behind are Greizmann and Fati and we desperately need 1 more runner. I'm betting that we see Vidal on for Arthur early in the 2nd half as he'll help with that.
Oh, and we're not really playing a 3-4-3 or 3-5-2. In attack, we are actually playing a 3-3-4 with Fati and Alba stretching the field and Greiz and Messi as CF. Setien is clearly trying to find a tactical solution to accommodate Messi and play the way that he wants to with controlled possession and pressing.