Neal Huntington gave a press conference almost immediately after the trade deadline ended. I thought a bunch of the things he said were really interesting, and I'd recommend you check the quotes out (you can find them just about anywhere that has a writer with a press pass on staff, but Bucs Dugout has a nice summary here). The quote that everyone's pulled out is, of course, this one:
We were willing to do something stupid. We just didn't want to do something insane. … Even the ones that we stretched into the stupid level, we found a cut-off point where it just didn't make sense to go beyond because of our confidence in this group.
That quote is magnified by Rob Biertempfel's report that the Pirates made "repeated attempts" for Giancarlo Stanton and that they made an offer that got the Marlins' attention before Miami ultimately decided that they couldn't trade the franchise's only marquee player. I have no idea what those offers would've looked like, but given Huntington's comments, you can guess that they probably included Gregory Polanco, a young pitcher (Taillon, Glasnow, or Heredia) and at least one or two other good prospects. Biertempfel also said that their reported interest in Mark Trumbo was geniune. Trumbo would've cost a little less than Stanton, in terms of prospects, but probably not a whole lot less.
This is all ex post facto now, but I can't help but wonder if Huntington's push to do something huge was borne more out of ridiculous demands for lesser players than it was an actual desire to pull of a mammoth trade. This is all hypothetical, but imagine that the Cubs were demanding Tyler Glasnow in exchange for Nate Schierholtz; wouldn't you rather see if you could get Stanton for Polanco and and Glasnow or Trumbo straight up for Glasnow or Taillon than to pay such a huge ransom for a marginal upgrade like Schierholtz?
This is all academic now. It's an interesting discussion for the off-season, because if Huntington was looking to make a megadeal at the deadline he might do so again over the winter. It's not the off-season, though, and the Pirates have a few things to look forward to between this just-passed trade deadline and the off-season.