Proven player > unproven prospects.. most of the time..
Agreed but the 2nd part of the analysis is what some people leave out .... sum of WAR of proven player for years under current contract is most likely much less sum of WAR of all unproven prospects traded for (before their FA hits). Otherwise, Guardians would be a crappy system trading away proven players who have more value than prospects. Otherwise, FOs would be a fool to just give away their players and upset their fan bases. Otherwise, the whole stock market system that pays people for waiting for asset values to appreciate would collapse (in other words, why FO are rewarded for waiting on prospects to mature -- get more for younger prospects than those about MLB ready).
There are thousands of trades that are meaningless .... there are hundreds of trades favoring the proven mlb player (Millers) ... but there are more trades where prospects are forgotten about until it all clicks ... Yordan Alvarez, Clase, Kluber and maybe Junior Caminero.
And unfortunately, each side of this argument can show hundreds of trades to prove their point in an attempt to be right (even me with that list above).