The argument in the summary is absolutely awful. Here's why:
First, let's start with two facts, and let's assume they are true: "the US has increased its crude production by about 2 million barrels a day" and "Iran's oil exports have been cut in half since 2011 (PDF), from 2.5 million barrels per day to a bit more than 1 million today". The implication in the summary is that Iran's oil production was reduced because the US increased oil production. Let's think about this for a second. This argument would make sense if all three of these claims were true: (1) Iran and the US were the only oil producers in the world, (2) The US was the only oil consumer in the world, (3) US oil consumption remained stable over the past two years. None of these claims are true. First, oil is a global commodity - there are plenty of producers and plenty of consumers. To put this in context, the global oil production is about 80-90 million barrels per day ( http://en.wikipedia.org/wiki/List_of_countries_by_oil_production
). So, why would it be true that an increase in 2 million barrels per day in the US would lead directly to a 1.5 million barrel reduction in Iran? Even worse, the US does not purchase any oil from Iran.(though there could be indirect effects, for example, a reduction in US oil purchasing could result in other nations purchasing more oil from Saudi Arabia or Canada, thus reducing their need to buy from Iran). If this is an indirect effect, then we would expect all oil-producing nations (*not* just Iran) to have a small reduction in oil sales (i.e. Saudi Arabia and Canada and Venezuela and other net-oil-export nations would all share in the decline).
In short, it's absolutely absurd to tie an increase of 2 million barrels/oil per day in the US to a 1.5 million barrel/oil per day sales reduction in Iran. These two things don't have any cause-and-effect relationship. They are merely correlated in time. (And I'd bet $100 that if the US never did any fracking, Iran would see the exact same decline in oil production.)
I can see the political implications of making this claim though: it allows (pro-oil) Republicans to pretend that fracking (which they support) resulted in forcing Iran (the country they hate) into a weaker position which pressures them to negotiate with the US. This allows them to take credit for Iran coming to the negotiating table while also undermining any anti-fracking talk. In short: if you damn liberals try to stop fracking, you're helping "Death to America" Iran. Why do you hate freedom?