What kind of team would be really interested in acquiring Bieber for one year?
A contender.
Why would they want to do that?
To vastly improve their chances to win immediately.
In that situation, what would they be willing to trade away?
Prospects, not core pieces of their offense. Trading away elite offensive cornerstones for an elite pitcher would merely be robbing Peter to pay Paul.
Trading Bieber will not solve immediate offensive problems.
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Conversely, what kind of team would be willing to trade away an elite hitter?
A team in rebuild.
What would they want in return?
A long term influx of young talent, meaning prospects.
If you want to acquire a significant upgrade in offense, it will require trading away significant prospects.
Over the years we have traded away multiple FORs with little team control remaining. How many established offensive upgrades have we recieved in return combined for CC, Lee, Bartolo, Bauer, Clevinger, and Kluber?
Not one.
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On the very rare occasions in which this FO has traded significant prospect capital for significant MLB upgrades, how many of those prospects ever became significant MLB players?
Not one.