In his final swim of the series, Thorpe posted a time of 53.59 seconds in the 100m butterfly to finish way back in 26th place.
While the five-time Olympic gold medallist was quicker than his previous marks in Singapore and Beijing, he has still only reached one final since his return.
"This week has been challenging, but has been very good," said Thorpe.
"I wish I could have done it with no one watching but that's unfortunately not the case. I am very comfortable with where I'm at."