Swans boss Michael Laudrup rang the changes for the game at Anfield, with the likes of Ashley Williams and top scorer Michu dropped to the bench.
Laudrup's understudies failed to grasp their chance and Monk, who is hoping to partner Williams at Wembley, acknowledged it was not good enough.
"No question about it, we got battered by Liverpool last Sunday," said Monk. "It was embarrassing and it's not ideal preparation for Wembley.
"It's wake-up call. We know Bradford are no mugs but if we beat them and lift the cup then the Liverpool result will be quickly forgotten by our supporters."
The long-serving defender added: "Winning would be the best thing in the world.
"It would be the icing on the cake for me because I've come from playing in the bottom league to playing in the Premier League with Swansea.
"I've got an LDV Vans medal, the Football League One trophy, won the Welsh Cup twice and the play-off final as well as winning the Under 16 Pioneer League!
"But none of them come anywhere near winning at Wembley on Sunday. To have a cup winner's medal around your neck is something you dream of as a kid and it would be the biggest medal for any of the players in our dressing room."