By James Hibberd
Updated February 07, 2013 at 05:18 PM EST

What’s happening to Modern Family?

Earlier this season, the acclaimed ABC series was the highest-rated comedy on TV. But CBS’ Thursday king The Big Bang Theory has since climbed to top the weekly chart hitting recent season highs, and Modern Family has slipped to No. 2 and relinquished its crown. Last night’s episode marks a season low for the show, down 10 percent to 10.1 million viewers and a 3.8 adults 18-49 rating.

What’s behind the slippage?

Well, its ABC neighbors sure don’t help much (or rather, its Neighbors). And Modern Family now has to contend with Fox’s American Idol, which has likely had an impact the past few weeks (one analyst noted that Modern Family tends to hit its low point around this time of year). Of course, Big Bang airs at 8 p.m. so it doesn’t even have a lead-in, also faces Idol, plus is an older show.

Perhaps it’s that Modern Family is rather ambitious and creatively complex with a large cast that seeks to work as a comedy with tinges of deeply heartfelt drama — pulling all that off week after week is huge juggling act.

The rest of ABC’s lineup had mixed results. The Middle was down 8 percent. The Neighbors was up 13 percent and Suburgatory went up 17 percent (thanks to Modern Family not running a repeat this week). On CBS, Criminal Minds tied its series low; CSI dropped 8 percent despite airing its well-promoted CSI: NY cross-over episode. Fox’s Idol led the night yet fell 16 percent for the start of Hollywood Rounds. NBC was largely down about 10 percent except Guys With Kids which fluxed up a tenth. On The CW, Arrow rose a notch and Supernatural was flat.

Full Chart: