Has "Happy Days" traditionally underperformed in syndication?

Not that it's never been completely off the air. The last time that I checked, Me TV airs it every weekday in the late afternoon/early evening (depending on your time zone). Happy Days first went into off-network syndication in 1979. The syndicated reruns actually aired under the title Happy Days Again to avoid confusion since first-run episodes were still being produced for ABC.

Somebody on Ken Levine's blog has suggested that the out-of-control applause whenever a main character (such as the Fonz) would make their first entrance was actually, a detriment to the series in the long run. At the time the first-run episodes were being broadcast, the audience reactions may have been justifiable since it could be looked at as hype in order to get the people watching at home as equally excited.

http://kenlevine.blogspot.com/2020/05/entrance-applause.html?showComment=1590631328831#c2384911286719787454

But after the mania surrounding Fonzie was over, people while watching Happy Days in reruns were left with purely judging the show on its comedy. And by the fourth season, Happy Days was more or less, coasting on lazy writing. This was based on the realization that they didn't have to be all that funny to make the audiences of the moment scream with delight.