Kopech has had fewer injuries and fewer surgeries and has more control and is cheaper. He was the obvious choice to keep. If they traded him they could have kept Ridin. However I wouldn't have for previously stated reasons.
If the team is different, they should LaRussa and Katz should mange them differently.as I stated previously I'm not a fan for the way Katz handled the pitching last year so you could be right here.
If the 2B is subpar defensively I don't like it.
They can have one pitcher who won't pitch the full season.For all the reasons stated earlier, Kopech was the better choice.
As far as this season goes I prefer to wait until we have all of the information as in the full roster before making judgements. Making judgements based on partial information is rarely a good thing.