"has been left flat" is correct and usable in written English.
It is usually used to describe a situation that has not been improved upon or had any changes or progress made. For example, "The economy has been left flat since the pandemic began last year."
With thousands of angry refugees stranded on the desert highway, and pro-Gaddafi gunmen still resisting inside the town, Libya's government has been left flat-footed by a crisis fast turning into its worst nightmare.
Devolution to English regions is a clever political tactic – nobody is really against it, the rest of the UK already has it in varying degrees, Labour has been left flat-footed and regional political elites are keen to grab whatever powers and responsibilities are on offer.
The British Association for Behavioural and Cognitive Psychotherapies, which has grown from 200 members in 1972 to 5,500 today, reports that four-fifths of accredited members now see private patients.Psychoanalysts and their therapeutic fellow travellers have been left flat-footed by the competition.
John Simpson (@thejohnsimpson) Forensics officers have been leaving flat of #Woolwich suspect Michael Adebowale, 22,w/ wheelie bins & bin bags twitter.com/thejohnsimpson… May 24 , 201310.48am BST This photo posted by Vinnie O'Dowd purports to show police at Macey House, Greenwich, the address of the second suspect, Michael Adebowale, around 20 minutes ago.
In recent years the company has been left looking flat-footed by rivals Apple, Google and Facebook.
The president's move has set the stage for a political showdown in Washington where the cable industry has been left looking flat-footed by a vocal and well- organised grass roots opposition.
A block of flats in Newcastle has been left "extremely unstable" and in danger of collapse after floods.
Family pictures had been left at the flat but had been turned away from the jury's view.
Her keys, mobile phone, purse and coat had been left behind at their flat.
In city centres, council estates and newbuild flats have been left out of BT's superfast broadband rollout, along with half of small businesses.
"Chasing Mavericks" fell flat and it appears the Halloween comedy "Fun Size" should have been left in its package.
