In one of his baseball abstracts in the mid 1980s, Bill James identified a hierarchy of positions -- hardest to easier. Players can commonly move down the list, seldom up it. As I recall, it was:

Catcher
Shortstop
Second Base
Centerfield
Third Base
Rightfield
Leftfield
First Base

Examples: Biggio moved from catcher down to 2B and now down to LF.

I'm not sure where CF fit. I can't imagine a 3B moving to CF so I've got it about right.

Important to this discussion -- Catcher was at the top. Catchers to move to other positions, but other positions do not move to C.

I was not aware that Barrett or Inge were not Catchers as amatures. News. I have never seen a mlb learn catching in the bigs -- not that I can think of -- other than a few utility IFs try to be a 3rd C just to get a roster spot.