A group of MPs that warned curbs on Police and Crime Commissioners are "too weak" have been particularly critical of Gwent commissioner Ian Johnston, who "persuaded" Chief Constable Carmel Napier to retire earlier this year.
Napier's retirement meant the formal process was bypassed.
The Home Affairs committee said the reasons given for the decision were "unsubstantiated by any concrete examples".
It also rounded on him for criticising the grilling he received about the move at the hands of Labour MP Chris Ruane, who represents the Vale of Clwyd constituency in North Wales.
"We were disappointed that, shortly after we took evidence from Mr Johnston, he took to Twitter to criticise a member of the committee for asking questions that he believed had been prompted by Gwent MPs, describing the proceedings as 'sad really'," the report said.
Three generations of the same family who died in a suspected arson attack in south Wales have been named by Gwent Police today as 46-year-old Kim Buckley, her 17-year-old daughter Kayleigh Buckley and her six-month-old grand-daughter Kimberley Buckley.
A neighbour of the child and two adults who died in a house fire in Gwent said she believed the victims were a 16-year-old mother of one, who was known to be pregnant with twins, who lived with her mother, aged about 46.
Sandra Gough, 64, lives a few doors away from the fire-ravaged home.
I heard banging and screaming at about 3am. It could well have been somebody trying to force their way in or out of the burning house. I would have tried to help if I'd gone out there, but I didn't know.
I thought the banging was coming from the nearby primary school. They're doing work there and I just thought they were continuing through the night. I thought the screaming might have been young people in the street.
It was only when I got up this morning that I heard what happened but I didn't realise it was so close.
I saw all the ambulances outside and the house was still smoking. It is terrible, absolutely horrific.