Thiago Silva is Thiago Silva and Rhodolfo is Rhodolfo. Two different players, two different stories. He's not guaranteed to be good just because Silva turned out to be so.
As said in one of the above posts. Most Brazilian defenders, including the top quality ones, leave Brazil at 23,24,25. It's the attacking talent that is being scouted in Brazil. Goalkeepers and defenders are left for last.
In short, his age says nothing. He just turned 25.
He's either good or he isn't, no matter if he's 22, 25 or 28.