The Oranje manager saw his tactical changes pay immediate dividends as Brian Brobbey struck twice inside the opening 17 minutes to put the Dutch firmly in control.
Despite the convincing win, Koeman stressed that his side must continue to improve, while singling out Brobbey for special praise, particularly for his movement and finishing on the opening goal.
"In that first goal was everything you want, we know that Brian is good at that," Koeman said.
"It starts with Bart Verbruggen, who puts him away well. And then we have a lot of speed, and Brian is again in front of the goal. You can't make a more perfect goal, starting from the goalkeeper."
The Netherlands wrote World Cup history by remaining undefeated for a record 18th consecutive time, but even after becoming the eighth team to score 100 goals at the World Cup and beating Sweden 5-1, Koeman remained critical of his team.
"Despite the 5-1 victory, you do see moments that if they start playing differently, it takes us too much time to recognise that, which meant we got into a little too much trouble."
The Netherlands conclude their group-stage campaign on Thursday, June 25th (Friday, June 26th, at 01.00 CEST) against Tunisia, whom they'll face at Arrowhead Stadium in Kansas City, MO.