Plus we never truly tried a hybrid double pivot with Busi taking up a little more attacking responsibilities that Xavi currently has while sharing the defensive responsibilities with another WC DM like Masch. It could be our go to plan for tough away games or against teams with intense pressing mentality (Athletic).Busquets played too much this season, he was absolutely exhausted at the end of it. Of course Masch and Busquets can rotate, even though Busquets will play most games. Having Busquets fresh at the end of the season is better than having him exhausted.
But yeah, Mascherano is going to see less gametime now that he is moved to the DM position than what he did at CB. He's 30 years old, and probably has no issue with this what so ever.
P.S, Happy Birthday to the man with a heart as big as the Nou Camp.