Spike TV has released the numbers for Ultimate Fight Night 22 -- a 0.9, which the Wrestling Observer notes is the lowest ever for a Fight Night live on Spike TV.

The Fight Night drew an average of 1.2 million viewers and peaked with 1.6 million viewers. This is down sharply from UFN 20 and 21 which both peaked at over 2 million viewers. 

Matt Bishop comments:

Although the number is startling to look it, it doesn't come as much of a surprise considering the nature of this card, which had a ton of changes and neither fighter in the main event is considered a draw (and Marquardt's last main event on Spike, at the first Ultimate Fight Night in 2005, was a universally panned fight).

The debut episode of The Ultimate Fighter season 12 got a 1.3 rating with 1.6 million viewers. 

Sherdog has more:

According to Spike TV officials, nearly 20 percent of the audience DVR'd the episode, so complete numbers will not be available until next week at the earliest. Still, the preliminary figures represent a downturn in viewership from Season 11, which debuted in March with a 1.8 household rating and 1.9 million viewers.

The series' 10th-season debut in September 2009 remains its highest-rated, as it shattered the network's previous ratings record for the show with a whopping 4.1 million viewers. The season ultimately earned the series its best marks ever, primarily on the back of former street-fighting sensation Kevin "Kimbo Slice" Ferguson.

My take on this is that Kimbo Slice gave the season a much needed boost, but that the "Kimbo effect" has completely worn off and the series is returning to its longer-term pattern of a slow but steady erosion in the ratings.