True but Chapman isn't just elite, Miller isn't just elite, they're basically the best of the best of the best and have been for years. Jansen and Betances probably round out the top tier of relievers over the past 3 seasons that Osuna has been around.
The Chapman and Miller trades both netted a top 30ish prospect and some throw ins. I don't think Washington would then find it agreeable to trade a top 10 prospect who they're probably counting in to fill part of Harpers shoes if he leaves, for more of a package that arguably the best 2 relievers in the game went for.... even if he's under control for three more seasons after this one. His arbitration deals will actually cost them money because he's got dem savez!
Chapman was a rental they resigned,, but Miller was under control.