You can't make trades with hindsight. The Cards had about a 20% chance to make the postseason at the trade deadline. Even now they are still under a 30% chance - where we'd immediately have to play a one game, 50/50 battle to get into the real 8 team playoffs. This team should not have been making major trades for only 2017.
The Cardinal way stuff sounds like what fans tell themselves to convince themselves that every guy on earth wants to take a big discount to play for this team. Most guys aren't going to do that. Especially not ones who are approaching their only chance ever to get paid. The Cards should not be trading for guys with the idea that they are magically going to take a 20% discount to play here after 2 months where they miss the playoffs.
I get the we have too many OF stuff, but that is something the Cards should use to improve the team for 2018 and beyond via a trade, not for a rental. I agree the D Backs didn't give up that much, but the "value" to the Cards of giving up almost anything for a rental was so low that this consideration was much less meaningful for us than for a team like the D Backs who were basically locked into a playoff spot by the end of July.