That is the reason why we can't have a double pivot with Busi in line up. He is not comfortable in that place.
Why not, we have played Sergi Roberto with Busquets a few times in midfield and it worked quite well
Not every double pivot must consist two Mascheranos
Most double Pivots consist of a pure DM, and a defensively solid dynamic midfielder/box to box. examples Juventus' Khedira-Pjanic, Bayern's Alonso-Vidal etc