Basically, as the senior among the conservatives, which Roberts is not, he gets to choose who writes the opinion in liberal/conservative splits.
Close, but no cigar.
If CJ is in the majority opinion -- he decides who writes the opinion for the court
If CJ is not in the majority opinion -- the senior most member of the court among those in the majority decides who writes the opinion for the court
In either case, the decision-maker can decide to write it himself or assign it to someone else in the majority.
Since Thomas is the senior-most member of the court, he always has that authority anytime Roberts is in the minority, which CNN laments is happening more and more. which they then conclude makes it seem "as if" Thomas is the new CJ.
Close, but no cigar.
If CJ is in the majority opinion -- he decides who writes the opinion for the court
If CJ is not in the majority opinion -- the senior most member of the court among those in the majority decides who writes the opinion for the court
In either case, the decision-maker can decide to write it himself or assign it to someone else in the majority.
Since Thomas is the senior-most member of the court, he always has that authority anytime Roberts is in the minority, which CNN laments is happening more and more. which they then conclude makes it seem "as if" Thomas is the new CJ.