That misses the point entirely, dave (as well as in effect buying into the notion that Labour can do much to move the polls at present).
The problem is - and was under Kinnock, Smith, Blair, Brown, Miliband and Corbyn - the media (and by that I mean the papers, radio/TV, the commentariat and social media). Pick up any of the papers on newsstands today, or read them online, or see what is being churned out across social media - there are hundreds / thousands of people actively engaged in pumping out pro-Tory nonsense, on every outlet you can think of and it is all the time.
When things go tits up - as they are with this, and as they will be over Brexit - even more of it gets pushed out.
All Labour can do is wait until a decision comes along that matters - ie: the next election - and then fight the campaign of its life, hoping that enough people believe their own experiences instead of what society is telling them. Win that and then we can start to fix things.