The problems with the Bulls screumming

Because there were question marks about the Bulls scrumming I studied that issue carefully when I watched the full broadcast of the game against the Chiefs.
Let me start off by mentioning that the Chiefs do not have a reputation of being strong scrummers.   They have had problems in scrumming even in games they won 0 for instance against the Stormers.  Their line out performance is definitely not top quality either.
However, i looked at the scrumming carefully and it became clear that they do have a scrumming problem.   In the first instance the main scrumming problem was on Greyling's side of the scrum.  He really had problems - but the question mark is is he the only  one to blame?
I then looked at Matfield as his lock supporter.   It seems as if there really is a problem. First of all when the pressure is supplied you see Matfield's back arching/bending - which means he provides very little support to the prop.   That is likely a major contributor to the problems encountered by the Bulls scrum.
I would like members to look at future matches carefully and see whether the problem I have identified is indeed in evidence.