Hi, I hope everyone is well.
I'm unsure why the three highlighted has' have been used in the way they have been...
'It is Ayestaran, a qualified fitness coach, who is credited with the rotation policy that HAS brought criticism and silverwear for Benitez at the Mestalla Stadium and Anfield and he HAS been instrumental in the improved fitness and sports science methods the Spaniard HAS brought to Liverpool.'
Rewriting the third section, is have used correctly, as in: He has been instrumental in the improved fitness AND sports science methods that HAVE been brought to Liverpool
Thanks