If Roger Ailes thought Glenn Beck's farewell tour for his final, televised goodbye on Fox News this month would generate a ratings boost as past fans turned in to toast Beck's slow motion send-off, the Fox News chairman must be disappointed because it ain't happening.

Instead, Glenn Beck, which just last year became a ratings monster for Fox News, is going out with a (relative) whimper, not a bang. In fact, Beck's ratings for May were among the worst he's ever posted during his Fox News run. In that sense, Ailes made the right move in cutting ties with Beck: His show's audience has shrunk by nearly one-half since early 2010, at the same time that hundreds of advertisers, put off by the host's hateful name-calling and often bewildering conspiracy theories, have pledged not to do business with Beck:

How much has the advertising exodus cost Fox News? In September 2009, ColorOfChange, which was instrumental in launching the Beck ad boycott, published its analysis. Based on advertising rates it concluded that Glenn Beck was bringing in approximately $600,000 less per-week (or approximately $2.4 million per-month), than it was before the boycott began. Keep in mind, that's when 50 or 60 advertisers had jumped ship. Today, that number hovers between 300-400.

Using that $2.4 million per month estimate, since the fall of 2009, it's possible the ad-starved Beck show booked nearly $43 million less than it would have if it weren't facing a boycott. $43 million.

With that kind of unprecedented Madison Ave. mass migration, Beck would have needed extraordinary ratings to justify continuing his contract. But Glenn Beck just could not consistently deliver those numbers this year.

Additionally, here's a look at how far behind Glenn Beck lagged in terms of the number of ads Fox News was able to even run during the boycott-targeted program.

Beck's program did flash signs of its former ratings life a couple times in recent weeks. The first came on April 6, which was the day Beck announced he was leaving Fox News. His program that night grabbed 2.2 million viewers, according to Nielsen ratings. The second temporary boost came during the three-day period following the news flash of Osama bin Laden death, of May 2, 3, and 4, when news consumers flocked to sources of information, and when Beck attracted audiences of 2.7, 2.4, and 2.1 million viewers, respectively. The problem is neither Beck nor Fox News can recreate those type of one-time news events, which means his program seems destined to limp off the air, a shell of its former ratings self.

In fact, those three bin Laden-spiked programs represented the only times during the previous month that Glenn Beck topped the 2 million audience mark. By contrast, early 2010, Beck's show used to attract 3 million viewers, and for the entire year it averaged an audience of 2.25 million. But those days are long gone.

For the first quarter this year, Glenn Beck drew 1.9 million viewers, a decline of 30 percent from the first quarter in 2010. And specifically in January, Beck's audience was 1.8 million, marking, at the time, his worst Fox News ratings month. In the just-completed month of May though, Beck matched that low water mark, once again drawing 1.8 million viewers.

So yes, Ailes' decision to take Beck off the air looks like a smart one, financially. It was Ailes' editorial decision to put Beck on the air in the first place, along with the host's cavalcade of hateful lies, that was the big mistake.