I don't think she's being brave enough......she should be smashing this shambles of a Labour Party all over the shop, but she and Ruth Davidson are playing it well up in Scotland. There are several distinct battles going on here........
Scotland is easily explainable because, with the SNP in power, its inevitable that it is going to be Nationalist vs Unionist, and the failure of Dugdale to in any way change Labour from the corrupt little mob it was up there has crippled its chances.
As for down here, I think her main problem is that the PLP have taken a collective decision to shut up during the campaign in an attempt to make Corbyn "own" the defeat. As with most of their decision making these past fifteen years, it is something both understandable and likely to blow up in their face if what they are planning for fails to happen. The consequence of this silence is that, if the media want to get a Labour voice on the election, they have to go to Corbyn or his allies, which means that its his message that is getting out without the internal opposition that it has had since he became leader.
edit: don't forget, it was only the summer 2016 coup that really killed Labour's poll numbers