Secondary schools in Wales' 2013 banding revealed
Twenty secondary schools have achieved the highest band rating - eight fewer than last year, according to performance rankings.
Ferndale Community went from Band 5 to Band 1, while Ysgol Y Moelwyn in Gwynedd had the best score in Band 1.
Education Minister Huw Lewis rejected criticism that the system was volatile.
"The system is there to teach us things about what we need to do next in each particular school and it is based on hard facts and reality," he said.
"I don't accept the point on supposed volatility," he added.
"Near to eight out of 10 schools once again have either stayed where they were last year or moved up or down just one single band so there's stability with the banding as a measure.
"But if schools have moved up or down and my advice to the head teachers and the governors particularly in those schools - also the local authorities they work with - is to get beneath the figures and really study what is going on in that particular school, whether it's good or bad."
Schools are graded on GCSE results, subject performance, attendance and pupils from poorer backgrounds.
Banding aims to identify where schools go wrong and how to improve.
A total of five schools dropped from Band 1 to Bands 3 or 4 with just under a half keeping a Band 1 rating.
Five of the schools who received a Band 1 rating were in Neath Port Talbot. Four schools have not been banded.
The bandings also showed Ysgol Ardudwy, Gwynedd, Ysgol Gyfun Bro Morgannwg, in the Vale of Glamorgan and Aberaeron comprehensive, Ceredigion rose from Band 4 to Band 1.
However at the bottom of the banding table in Band 5, Barry Comprehensive in the Vale of Glamorgan and Ysgol Cymunedol Y Dderwen in Bridgend received the worst score of 44.
After the publication of the bandings on Thursday, Welsh Liberal Democrat education spokesman Aled Roberts said: "School banding system is too simplistic.
"No matter how schools in Wales have performed over the year, we already know that there will be a fixed amount of schools in each band.
"That is too crude and simplistic a system. Too often we are hearing of how parents are confused about why their children's school has been re-banded despite the fact its results have stayed the same."
Plaid Cymru AM Simon Thomas said: "Plaid Cymru believes that banding does not provide a whole view of a school's performance.
"We have always maintained that a constructive evaluation process which leads to targeted support should be adopted, instead of creating league tables through the banding system."
Meanwhile, Shadow Minister for Education Angela Burns AM, questioned an "unconvincing and unproven" system.
"If we are going to measure school performance, the systems involved should be fair and equitable, and comparable like-for-like...
"There is potential in the principle of banding and I passionately believe in increased transparency for parents.
"At a time when education remains at an all-time low in Wales, and the shadow of Pisa results continues to fall over Carwyn Jones and Welsh Labour, a more effective and trustworthy system is desperately needed."
Welsh teaching union Ucac said each new set of banding results emphasised "the meaninglessness of this process and any information that emerges from it".
Chris Keates, general secretary of the NASUWT teachers' union in Wales, said the banding system was "fundamentally flawed and stigmatises teachers, schools, pupils and local authorities".
"The original intention behind banding, to ensure that funding reflected the challenges faced by schools, had some merit but the banding system has become distorted and discredited," he said.
One of the two worst performing schools in the ratings was Coleg Cymunedol y Dderwen in Bridgend. Headteacher Andrew Warren said there were factors that affected the result and it would change quickly in future years.
"The school is a new school which opened in 2011 combining Ogmore and Ynysawdre comprehensives. Combining two complex organisations is a challenge in any circumstance," he said.
'Improve next year'
"Until August 2013 it operated on a split site at the two previous school buildings which created problems with a sense of identity, communication and teachers moving around.
"We were also managing a £3m new build although we are, since September, occupying a fantastic new building."
The banding was "not a surprise - the results were very, very poor and we are very disappointed," he said.
"We know however that we will rise dramatically next year as we already have improved attendance figures and (from careful monitoring and intervention) this year's GCSE students will have much improved results," he added.
"Now it's a case of picking up on the morale of staff who could not have done more in challenging circumstances - it is not their fault.
"I've worked at six different comprehensive schools and the children here are fantastic and really have the most potential."