It wasn't much of a surprise when Ultimate Fighting Competition champ Chuck Liddell took the long walk on ABC's Dancing With the Stars Tuesday night.

And that's the problem.

Reality TV shows are always a delicate mix of factors -- especially on competition shows, where so much of the action comes from participants reacting in the moment. But this season's edition of Dancing With the Stars seems to have a particular lack of buzz, despite its status as one of the highest-rated shows on the schedule.

And Liddell's exit offers a few clues.

Consistently clumsy onstage, he's one of the competitors in DWTS' mushy middle -- too mediocre to offer much entertainment, but not wacky enough to stand out as comic relief.

And he's not alone: among a record number of competitors, former NFL star Michael Irvin, snowboarder Louie Vito and even Iron Chef star Mark Dacascos have hovered in that area -- not really compelling and just awful enough to distract.

As the New York Times reported Tuesday, the show has seen a 20 percent drop in viewership among key audience groups this season, as its median age has grown to 57 for the performance shows and 58 for the results. In other words, the cool kids are looking elsewhere as the show flounders in a flood of forgettable competitors.

I think there's a few things going on here: Fox's So You Think You Can Dance is the more youthful show, and is airing against DWTS in the fall for the first time; the show started with too many celebrities, and so we're stuck with long weeks waiting for the mediocre dancers to get bounced; and the competition's strongest dancers haven't stepped up enough -- rapper/singer Mya is the only competitor who has consistently wowed judges, nearly a month into episodes.

As the competition gets stronger, expect interest to pick up. But DWTS is showing its age these days and producers have been served notice; time to really reinvent the show or risk it falling into irrelevance.

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