I think he knew he couldn't go after the other guys either because ownership told him to stay under the luxury tax, so he got creative with Schwarber thinking outside the box. Here's a guy who might have a similar upside to Rizzo/Cruz, will cost a fraction of the prospects because he's on the D.L. and management will approve of the trade because he stays under the tax limit.
Sometimes, you do the best you can, with what you have. DD might have made the trade for Rizzo, and if the FO told him he had to stay under he'd be giving up Casas/Yorke + to not eat the money.