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.
Former police officer Ian Johnston has stopped Labour taking Gwent in the police and crime commissioner elections.
Mr Johnston beat Labour's Hamish Sandison in the final round of counting and became Wales's second independent candidate to win in the polls.
Turnout across Gwent was 14.3% - and one of Newport's 100 polling stations had no voters at all yesterday.
The boyfriend of a teenaged mother who died in a blaze which claimed the lives of three generations of one family was being held by police tonight.
Kim Buckley, 46, daughter Kayleigh, 17, and six-month-old Kimberley died when fire ripped through their home in Cwmbran, south Wales, early this morning.
Kayleigh had recently given birth to twin daughters and was still coming to terms with the tragedy of losing one shortly after birth.
Carl Mills, 27, the father of the twins, was named locally today as the boyfriend arrested by police on suspicion of murder.
Neighbours of the victims of the house fire in Cwmbran, Gwent, have spoken of their shock at the deaths.
Tania Brown, a friend of the Buckley family, told ITV Wales she "just wanted to cry" when she learned.
The victims were earlier named as 46-year-old Kim Buckley, her 17-year-old daughter Kayleigh Buckley and her six-month-old grand-daughter Kimberley Buckley.
Police have paid tribute to two residents who "valiantly and bravely" attempted to rescue them, but were forced back by the flames.
Chief Inspector Steve Corcoran described the fire as a "tragic and horrendous incident."
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.
Gwent Police are searching for witnesses after three people, including a child, died in a house fire in Cwmbran, South Wales.
Anyone with information about the incident or who may have witnessed something suspicious at the address leading up to the fire are being urged to call 101 or Crimestoppers on 0800 555 111.
Two adults and an infant were killed in a house fire today in the Welsh town of Cwmbran, Gwent Police have said.
A 27-year-old man has been arrested on suspicion of arson.
In a statement, Gwent Police said forensic investigations will begin this morning, adding that officers will also be conducting house to house enquiries in the area.