The text of Szubin's speech is available here: https://www.treasury.gov/press-center/press-releases/Pages/jl0419.aspx
Sections are titled "The JCPOA: A Sanctions Success Story" and "The Benefits of the Bargain." You get the idea. He ended with a flourish labeling the agreement "deft diplomacy."
Having been at Treasury, I understand how these remarks are drafted and cleared. I assume they were reviewed by both the State Department and the White House. But Adam Szubin, just because you and the administration call something a "bargain" and a "success" and "deft diplomacy" doesn't mean that it is. While I do not doubt the premise that sanctions brought Iran to the negotiating table, the true legacies of the JCPOA will be a case study of naivete, a much more dangerous world, and disastrous results.