Archbishop Michael Neary's predecessors in the Archdiocese of Tuam were defensive, internally focused and lacked awareness of victims' suffering, a Catholic Church review has found.
Joseph Cassidy and Joseph Cunnane were also slow in acting against accused clerics and delayed taking priests away from their day-to-day duties.
Despite the failings in the 1970s and 80s, the National Board for Safeguarding Children in the Catholic Church (NBSCCC) noted a change in attitude since 1995 and found "a willingness to recognise and learn from any mistakes".
After Archbishop Neary took charge child safety became a priority and all complaints have been passed to gardai, including some historical cases.
Allegations have been made against 18 priests, the NBSCCC said.
Twenty-five complaints were referred to gardai and 26 to health authorities. While 10 of the priests are dead, eight have left the priesthood and two have been convicted of abuse.
The archbishop's approach to allegations has been marked by thorough inquiries, considerable interrogation of complaints, industrious and diligent analysis and a quiet resolve. However, the NBSCCC found resistance when the archbishop asked priests to step aside.
"It is to his credit that in spite of opposition, Archbishop Neary has maintained his authority and kept some men out of ministry where there is evidence to suggest that they should be viewed as dangerous and should not have access to young people," the report said.
Ian Elliot, chief executive of the watchdog body, said Archbishop Neary had laid the path for allegations to be dealt with promptly and appropriately.
"We are confident in his decision-making and in the support he gives to those responsible for dealing with allegations as they emerge," he said.