Voth and Fedde are pretty big indictments of the Nats development staff and the ability of the coaches to translate analytical data into usable information prior to Doo. They knew what they had in Voth with his spin rates, there were articles about it, yet they could not tap it. The Os were able to for a while, but frankly, they have an abundance of riches there. There's a reason that around 2019 the candidates for 5th starter - Ross, Fedde, and Voth - all looked promising. They all had talent that should have filled out some rotation slots after Anibal and others moved on.
