So for example, assuming Liz Kendall is the first one eliminated, very few of her second preferences will go to Corbyn, but the numbers are small enough not to be decisive. But if it Andy Burnham who goes out next, that's where it gets interesting, as you'd imagine more of his support would go to Corbyn than would Yvette Cooper's.
Be interesting to see a poll that tries to break down how this support is allocated. My suspicion is that for Corbyn to have his best chance, he's better up against Cooper in the run off than Burnham.