Starc's run started at the 2015 World Cup, stretched through the 2019 edition and has been maintained over five games so far at the ongoing tournament in India.
In 23 matches, he has a total of 56 wickets with a career-best of 6-28 against New Zealand in Auckland in 2015.
"I think in 50-over cricket there's the new ball, the middle phase and the last phase and it's pretty hard to nail all three," said Cummins on Friday.
"He's one of the rare bowlers that swings it up front, but you can basically give him the ball at any time and you feel like he's going to create something. He just keeps getting better and better."
Starc's unique record made him the top wicket-taker at the title-winning 2015 World Cup when he claimed 22 victims as well as four years later when he added a further 27.
In India so far, he has seven and will be hoping to keep his streak alive when five-time champions Australia face neighbours New Zealand in Dharamsala on Saturday.
"He's wobbling the ball across right-handers, he's bowling round the wicket probably more than he did in, say 2015, he's got plenty of tools at his disposal," added Cummins.
"It's pretty amazing he's been able to keep up the pace for that long as well."
