It is hard to argue with Grant Brisbee putting the A's in the "loser" side of his winners/losers wrap-up of the trade deadline, considering they're one game back of the playoffs and five games back of the division leaders, yet decided only to add a late-inning bullpen guy. He came practically free, in prospect terms, so that part's a win, but this is still a team relying on the following starting rotation:

Pitcher	DRA
Sean Manaea	3.74
Brett Anderson	7.52
Edwin Jackson	5.11
Trevor Cahill	3.02
Frankie Montas	5.97
Paul Blackburn?	4.03
Daniel Mengden?	5.72

That's barely a big-league rotation, much less a playoff one. Here's a list of the starting pitchers who were traded:

Pitcher	DRA	Notes
Matt Andriese	4.12	Including him even though he's been an RP this year
Chris Archer	4.68	Cost two very good prospects
Nathan Eovaldi	2.98
Lance Lynn	6.86	*coughs*
J.A. Happ	4.15
Kevin Gausman	4.06
Cole Hamels	6.35	$22.5 million salary + $6 million option buyout

There are players on this list who would have helped the A's. Eovaldi, Happ, Gausman, and maybe even Andriese are better than Frankie Montas, Edwin Jackson, and Brett Anderson, and they're all active and pitching now, which makes them more valuable to a team than Paul Blackburn. None of them cost that much in terms of prospects or cash. (Happ's $4.6 million remaining on his contract is tops of that group.) You can argue your way out of each of them, sure—Andriese is mediocre reliever; Eovaldi is going to break; there's no budget room for Happ; Baltimore's price for Gausman outstripped his actual value—but you can do this with every single player you could ever think about acquiring. There's always a reason not to. It sure seems to me like the reasons to outstrip the reasons not to for the A's as they existed on July 31, 2018.