And I'd guess it took a couple of years for them to realise that the candidates they took in in 2020 and onwards were underperforming compared to previous years

And I'd guess it took a couple of years for them to realise that the candidates they took in in 2020 and onwards were underperforming compared to previous years, and that this was the cause, as opposed to any of the other things that have changed since 2020.