CBS Evening News Has Its Lowest Viewership Since Couric’s Premiere

> Update: 12:46am:”Katie’s brother-in-law died suddenly last week. That’s why she wasn’t back although Russ said she would be,” an insider says. The funeral was held on Friday.

Katie Couric‘s ratings “just don’t budge much,” an e-mailer observed recently. But last week, with Couric absent from the anchor desk for three days (during sweeps!), the ratings declined significantly.

Russ Mitchell subbed on Monday, Tuesday, and Friday. (Strangely, Mitchell on Monday said Couric would be back on Tuesday… but she wasn’t.) The CBS Evening News averaged 6,910,000 total viewers for the week — its lowest delivery since Couric took over in September, according to TVN’s weekly ratings post.

The CBS broadcast’s previous low came the week of Oct. 2, when it averaged 7,038,000 viewers…