The only plausible explanation would be that he wants experience specifically against Barca. IIRC, Miranda was a starting CB when they defeated Barca in the CL. He also has same (probably even better) level of synergy with Skrinko, so I doubt that's gonna be an issue.
No Nainggolan, Brozo definitely isnt 100%. Play 5 defenders, pack the midfield and hold out for 1 point. Messi or no Messi, Barca still have a superior squad.
Why the hell are we starting Miranda this game when it's been proven beyond a doubt that De Vrij - Skriniar is our best CB pairing? And against Barcelona of all teams!