Season five of the acclaimed drama, poached by Sky from the BBC for the launch of Sky Atlantic in 2011, was seen by an average of 72,000 viewers across its double episode premiere on the Sky exclusive channel on March 27.
Episode one pulled in 98,000 viewers, while episode two slumped to just 45,000. In contrast, the season four premiere on BBC Two was seen by 360,000 last year.
However, Naomi Gibney, the acting director of Sky Atlantic, accused "one or two people" of making "misleading conclusions" about the show's popularity due to the viewing figures.
In a post on the Sky Views blog, Gibney said that Mad Men is available to more than 10m Sky homes, which is around half the amount it could reach on subscription-free TV platform Freeview.
She also said that taking into account the number of people who caught the show in the seven days after transmission via Sky+ or video on-demand service Sky Anytime, it is actually "more popular than ever" on Sky.
"Back when it was on BBC Four, the biggest ever audience for Mad Men in Sky homes was 141,000 viewers (for the very first episode of Season One in 2008)," said Gibney.
"By contrast, the first episode of Season Five was watched by a total of 209,000, an increase of almost 50%. The average for the first three episodes of this series is 142,000, which is 38% up on Season Four in Sky homes. But this isn't about who got more viewers than who. Ultimately it's about creating value for customers."
Echoing the recent statements of Sky1 controller Stuart Murphy, Gibney claimed that Sky+ recording and on-demand have made the "live" premiere for linear TV shows "far less important that once was the case".
She claimed that during Mad Men's latest series, 79% of the total audience had watched the show via 'timeshifted modes on Sky+, Sky Anytime and multiplatform service Sky Go'. The story is similar for other Sky Atlantic shows, such as Game of Thrones and Boardwalk Empire, she added.
"In other words, audience behaviour is changing dramatically as people take advantage of all the different ways to catch up with their favourites," said Gibney.
"These days, to measure how successful a show is, we need to look at how it is enjoyed across all platforms it's shown on. It's not just us who realises this - the BBC too have recently launched a new measurement system (called Live+7) that does exactly that."
She added: "Anecdotally, we're all aware of the trend for people to stack up episodes on their Sky+ box to enjoy in a single viewing, the same way they might watch a box set.
"We go out of our way to offer all that flexibility to Sky customers because it really doesn't matter to us how they choose to watch - live, on-demand, on the go, or catch-up. So, if some commentators continue to fixate on ratings for linear TV premieres, perhaps it's time for them to catch up too?"
GIbney concluded by saying that Mad Men's popularity should not be judged on how many viewers it gets for each episode, but the passion and devotion of its fans.
She said that serving this audience is what a pay-TV business such as Sky - which is not so reliant on viewing figures for revenue - should be doing.
"The success of Mad Men - and the reason why it is such great TV - has never really been about the size of the audience. There are, and there always will be, many other shows that get more viewers," Gibney said.
"But there are few which inspire the same levels of passion and devotion among their fans. That's why Mad Men makes such sense for a subscription business like Sky.
"We're much more interested in keeping our customers happy and loyal than the audience for a premiere of any single show. For those of us who are hooked on our weekly dose of life at Sterling Cooper Draper Pryce, nothing comes closer to that goal than Mad Men."
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