I'm going to suggest Marshall knew the screen was coming and had her acting skills in order.
Listening to Diana, she pointed out that the play didn't/wouldn't have gotten Paige open. At best, she would have had to launch a contested 3 as Steulke rushed over with Marshall coming. End of the quarter finishes have been a thorn for UConn this year when they have the ball.
You win or lose the game with your best player. Too many times in the 4th, Paige went to corner and didn't get involved or touch the ball. I don't know if it was by design, but Paige didn't look or act like the player who was killing it in the previous 7 games. Yes, Marshall did yeoman's work guarding Paige, but Paige helped her out, responding too passively. She had a size advantage and seldom drove to the basket or tried to shoot over Marshall.
The game should not have come down to a last play or poor call. UConn had plenty of opportunities in the first half and failed to exploit their lead. You see it all the time in sports. One team has the lead for the entirety of the game, but allow the other team to hang around, and the outcome is determined by one or two plays, an officials call or a game-winning shot.
I'm still surly this morn, but by tomorrow afternoon, I'll realize that UConn would be running into a buzzsaw that is SC if they had beaten Iowa.