Garcia is better at the moment then both of them. Dinho isn't a natural CB to begin with, but since Garcia has been playing there since he was a kid. TBH is still young and needs time to develop. A big factor why Pep is picking Garcia above all the others is because how good he is with his feel. People may not think this is not a big deal, but when you can move the ball quicker, you start the attack quicker. He can distribute the ball better into midfield and out on the wings. Of course you will need to defend and he isn't perfect, but keeping the ball means less defending overall.