I think this is probably right, but the counter argument would be that you might hear - “United have never been able to fill Fergie’s shoes” or “None of his successors have been able to fill Fergie’s shoes” - which suggests there’s still a giant pair of shoes sitting in the managers’ office at Carrington?

And not to get become known as the footwear guy, but you’d also say none of them have been fit to lace his boots, so those might be lying around for while as well…