I think he has potential on the bases but it's much harder to teach routes and reading the ball off the bat which obviously is his biggest issue in the outfield. He doesn't need to steal bases (I feel like his first step might be a tad slow) but at the very least he should be able to become a valuable baserunner as long as he's always looking at his coaches.
You traded an elite closer for the opportunity to roster a 20 year old with no power in AA in a supposedly competitive year. I'd say woe is you indeed.
You must be new to relievers. They just...stop working sometimes. If he manages to stick in the league he could just as easily be an elite reliever next season, it's just how it goes.
In the Cooper deal they also gave away Caleb Smith who has turned out to be quite a capable starter.
They were part of the three team Steven Souza Jr. deal between the Rays and D-Backs. They acquired Brandon Drury and gave up Nick Solak and Taylor Widener so that was just a truly awful deal for the Yankees, even if they did acquire half a season of JA Happ out of it. They also traded away Sonny Gray for little and he's doing very well in the NL Central.
That's not to say any of those players are stars, but the Yankees aren't infallible. They have a ton of resources and they make a lot of good moves but Cashman isn't the f***ing boogeyman.