I think Malloy is more handicapped by his glove rather than where it is positioned. Or maybe its his arm. Or maybe both, I don't know.
As for last season, he was at 3B from Opening Day through May 29. Then he was in LF/RF from May 31 through August 20, save for one game at 3B. Then he finished out the season at 3B. And there were some PH/DH duties in there as well. So, he was given continuous blocks of time to work at 3B then OF then 3B. He was moved around from game to game. I think it should be acknowledged that he was given game after game to work in the dirt and in the grass on a consistent basis.
I don't mind the optionality, but I don't believe that it is for everybody. And I don't know that the whole team should be moving around defensively on a game to game basis. I wouldn't expect that. The catchers are going to catch. Baez at SS, Meadows (if he sticks with the big club) at CF, Torkelson at 1B. That's half of the defense right there. Greene as a COF or CF, Carpenter and Canha as COFs, however it lines up, and maybe Vierling in the OF as well. Hopefully Keith can handle 2B, and so then there's the rotating door at 3B. It's probably not going to be as fluid as last season.