Its a statement Andy O'Shea, Ryanair's Head of Training, has repeatedly made in public, in fact one of two. The second is that as far as he is concerned there is no difference in quality of applicants between integrated students and modular. The 50% claim is usually followed by an admonition to the training industry about their claimed attempts at 'selection', because by his standards it is completely ineffective, 'selected' integrated students being indistinguishable from not selected modular students.
In common with many airlines Ryanair select and train to competency based standards,
AFAIK no ATO trains to competency based standards at the ab-initio stage, so a disconnect in standards seems inevitable.