But why exactly is it too much, if KP has the means to find similar players in the future? Why can't it be just like trading a closer in baseball? Valuable player, sure, but easily replaceable.
If I understand you correctly, if Charlotte values Frye as a lottery pick PF, that means Portland should value him likewise? That still doesn't change the fact that he's a bit player in Portland's system, and likely will be until the end of his contract. So regardless of how highly other teams might value him, his actual value to Portland is very low. Therefore, his only value to the Blazers is as a trade asset, in which case the only problem with trading him in this deal is that he might bring back more later, which personally I highly doubt.