Ryan says the small screen sizes and the inability to create much demand to date for mobile ads are bad signs. Despite that evidence, he says he’s learned quickly that “the answer that people want to hear is that mobile is going to be huge.”

But perhaps Ryan isn’t the most impartial party to ask. He left DoubleClick three years before Google paid $3.1 billion for the online ad delivery company in 2008. He benefited when that acquisition flew through the regulatory process, receiving clearance from EU antitrust regulators after the U.S. said the deal did not pose a competitive threat in internet advertising. Now, it’s that quick decision that may be holding up Google’s $750 million acquisition of AdMob. (Who knows, maybe Ryan is throwing Google a bone by downplaying the opportunity in mobile?)

After all, the head of WPP (WPP.L), the world’s largest advertising group by sales, told Reuters that regulatory authorities should look closely into the acquisition, citing Google’s dominance online thanks to the DoubleClick acquisition. “I don’t think in the case of DoubleClick it was deep enough and strong enough,” said WPP’s CEO Martin Sorrell. “It (regulatory investigation) should be rigorous. Our clients will welcome a close look.”

There’s always a chance that publicly made comments are taken into consideration by regulators, who are now on track to make a decision by the end of this week, according to the NYTimes, which cites unnamed people. A source told us that next week isn’t out of the question either.