Back with a bigger cast, colorful challenges, new voting twists, that $500,00 grand prize and for a longer season, Big Brother (2.1/7) returned last night for its 15th cycle. The CBS reality show took a hit right out of the gate. Watched by 6.1 million viewers, the veteran Julie Chen-hosted series was down 19% adults 18-49 from its July 12, 2012 season debut. That ties the series’ lowest season premiere ever (the July 13, 2008 season bow also pulled a 2.1/7). The Season 14 premiere had dipped 7% from the previous cycle’s bow but pulled in a four-year premiere viewership high with 7.09 million viewers. The viewership for last night’s debut was the lowest since 2008. Meanwhile, Still undeflated despite its low May 29 start, The American Baking Competition (1.2/4) was even with its June 19 show, which was even with the week before. Now in a 9 PM slot, the Jeff Foxworthy-hosted freshman reality series did see its viewership slip from last week’s high of 5.8 million to 5.05 million.

On Fox there was more cookin’ on MasterChef (2.3/7). With last season’s winner Christine Ha returning to help this year’s contestants through an elimination challenge, the Gordon Ramsay-led show bopped up 5% from last week among the key demo to emerge as the highest-rated show of Wednesday night. Fox won the night in adults 18-49 and total viewers.

On ABC at 9:30 PM, How To Live With Your Parents (For The Rest Of Your Life) (0.9/3) wrapped its freshman season. The now-cancelled comedy produced by 20th TV was down 10% from last week for a new season low. Earlier in the night, another DOA ABC comedy, Family Tools (0.7/2), was also down. Falling 22% from its June 19 show, last night’s result was also a season low. The network ended its night with Nightline: The Lookout (0.9/3), which was down 18% to hit its season low too.

NBC and the CW were all encores Wednesday.