I do believe La Strada was a 1 hit flop.
Speaking of flops, since someone else resurrected a discussion on Ken Mandelbaum, I hope he does a sequel or update to "Not Since Carrie". I love that book, and have re-read it a couple of times.
Maybe he could do British flops (since I enjoyed the "What a Carrie On" thread on the West End board). I especially was interested in all the shows that played decent to boffo box-offices here, and then flopped over there.
Xanadu! Can't cry on cue!