I listened to that podcast. He didn't outright say it, but I thought he (and others tbf) have been taken aback by the cost of some of the trade targets. As I said the other day, there's no 16' Sale out there ready to be moved, yet the prices seem very much to be asking for a return for that sort of calibre.
I don't really know how you get around that if you're not developing pitching yourself. They're clearly not looking to sign anyone off the top of the shelf.
I guess one option is trade the second level prospects for pitchers still very much unproven.