Three and four years ago in ST, I got the chance to watch TK work with Sano on one of the smaller infield skins. Interesting couple of sessions a year apart. Both in how Kelly works, and how little progress Sano had made over they year in between. (He got hurt after that.) By my eyeball test, Sano may never be 'average major league caliber' defensively. I'm not piling on here, but there has hardly been any discussion on why folks think he could be called up to play 3rd. That would be a grave mistake at this point. He's young, and it could work out someday, But not in the very near future, imo.