A lot of people are focused on the wrong angle of the WTOP story. It is very impressive. But there are some things that need to be remembered.
WTOP switched to FM because their signal at 1500 on the AM dial, even though it was 50,000 watts, was a bad signal for covering the sprawling DC metro. It was great is some areas, but unlistenable in others. That's why they switched to FM. But WTOP has been the top biller in DC for two decades, even when they were on AM.
WTOP also did a simulcast, AM & FM, for a several books (Diary, not PPM) so they could gauge the success of the FM before ending the simulcast on AM.
WTOP also has very little true competition. WMAL is their only real commercial competitor and that station has gone through so many changes in just the past 5 years it's laughable.
The Bonneville brass made, IMO, the mistake of applying the WTOP plan to both Phoenix and Seattle. But the difference is KTAR and KIRO are both blowtorch AM signals with excellent coverage of their metros. And sadly, both KTAR-AM and KIRO-AM are now middling sports stations in the bottom half of ratings and billing in their markets. And both, ironically, have enormous payrolls and expenses.
Unfortunately, we'll never know how well the old KIRO-AM or the old KTAR-AM would have done in PPM. We know that both used to rule the ratings and in some markets those kinds of AM stations are doing very, very well in PPM. We'll also never know if the old KBSG-FM would have been a ratings powerhouse in Seattle. We do know that similar formats are at or near the top in a number of markets with low expenses and enormous revenue.
While many people are praising Bonneville and other companies for switching to FM. There are some, myself included, who feel that these moves are not so wise and don't apply in all situations.
Remember, in the list of the top 10 billing stations in the U.S, 5 of the top 10 are AM stations.