Isla: Bielsa has revolutionised Chile
"The great virtue and merit of having qualified for the World Cup is only his," the 21-year-old midfielder told Reuters in a telephone interview. "We players know we are the ones who play but he revolutionised the country.
"He built a team with very young players who had got no chance of playing in the senior team."
Chile, who face Spain, Switzerland and Honduras in Group H at the finals in South Africa, achieved several milestones in qualifying, including a first competitive win over Argentina.
They will be appearing at their first World Cup finals since 1998.
Bielsa tried out 37 players and formed a good nucleus by the fifth of their 18 matches in the South American group, a 2-0 win away to Bolivia at altitude in La Paz.
"He arrived in Chile and changed quite a lot of things, he worked on things we had never done and, thank God, it worked with a great campaign in the qualifiers," said Isla, who plays for Italian club Udinese.
"He tries to plan a good game depending on how the opponents line up and how we can complicate them and if we play badly never mind. He's not the kind of coach to hold you responsible for mistakes."
Isla identified Argentina captain Javier Mascherano as his ideal midfield role model.
"I really like the way Mascherano plays," he said. "It's good to observe. I'm a very young player who likes to watch a lot of other players to be able to copy the good things they have," he said from Italy.
Both Isla and Mascherano made their international debuts under Bielsa, who coached Argentina from 1998-2004.
Mascherano made his Argentina debut against Uruguay in a friendly in July 2003 when he was just 19.