Chhetri was speaking to the media on the sidelines of India's Intercontinental Cup campaign where they take on DPR Korea on Saturday.
In the opening match of the tournament, India lost 2-4 to Tajikistan despite taking a 2-0 lead in the first half. Chhetri netted a brace in that match.
Chhetri plays for defending champions Bengaluru FC in the ISL, which made its debut in 2014.
Citing the example of Sandesh Jhingan who plies his trade for Kerala Blasters, Chhetri said he had a conversation with the India defender about how the players came up against better footballers in the ISL as compared to the Asian Cup earlier in the year.
India were clubbed with Thailand, UAE and Bahrain in group A and finished last despite a strong 4-1 victory over Thailand in Asian Cup.
"Sandesh Jhingan is much more aware than any player you could think may be 15 years back. He is more knowledgeable. He is much more equipped to do well," Chhetri said.
"I told this to Sandesh that when we played Bahrain, UAE and Thailand, he did not face a Miku, (Manuel) Lanzarote, Coro (Ferran Corominas), but in the ISL he faces them.
Miku is Chhetri's teammate at Bengaluru FC while Lanzarote plays for ATK and Corominas turns out for FC Goa.
"Those were top teams but they didn't have a Coro, a Miku or a Lanza. They are good players. I am not saying they are world class, but these are top players.
"So Jerry (Lalrinzuala), Sandesh and Anas (Edathodika) are playing with them and that's why they have improved. Whatever improvement you are seeing is because they are training with them," said Chhetri, who recently won the AIFF Player of the Year award for a record sixth time.
"These are small things that have changed in the last five years. But where you want to reach is here. That's why whatever we do is less. We need to put our heads down and keep working hard," he concluded.
( With inputs from IANS )