Gregory reached the zenith in his very first season, back in 2017-18, when he led the Marina Machans to the ISL title. However that was followed by a nadir of the lowest order when the team's title defence went horribly wrong and ended up having the worst season ever recorded by an ISL team.
To make matters worse, the team crashed out of the AFC Cup as well in the group stages where they were pipped by Bangladeshi champions Abahani Dhaka. As such, many were surprised when Chennaiyin FC management decided to hand the Englishman another contract that would see him take charge of the team for the upcoming season.
Gregory feels the management's faith in him to change things around convinced him to stay and start afresh.
"My contract was expiring (at the end of last season). I spoke to Vita Dani (Co-owner, Chennaiyin FC) and she wanted me to stay. She wanted me to continue this season and,she offered me a new deal. After some deliberation, we agreed on everything. It didn't take as long, I think, because, she wanted to change things. I think, as a group, we made a lot of mistakes in many, many departments," he said.
"Back in England, there are clubs that are 120 - 130 years old. They've been making mistakes. We've been here for only five years and we made a lot of errors on and off the field last season. And obviously the responsibility always comes back to me. It is always my fault because I am the coach," he added.
"But this year, we've learned from our mistakes. And we decided to take a completely fresh approach to everything, to choose to change a lot of the plans from last season."
The Englishman reiterated that there was a much better environment around the team after the negative spiral they had found themselves in last season.
"Generally there's a much better feeling and belief in and around the camp. We started last season as champions and a lot of maybe didn't work as hard as we had done the year before. We didn't quite have the same togetherness that we had in season four (2017-18 season). We've obviously recreated that again this season with the changes that we made. We only kept one of our overseas players from last season."
One of the major overhaul that Gregory has undertaken is in his overseason department where only Eli Sabia has been retained from the disastrous last season. The rest, including fan favourite Raphael Augusto, have been let go.
The 65-year-old underlined the importance of having a strong foreign contingent and highlighted the way the likes of Bengaluru FC, Mumbai City and NorthEast United built their squad around a strong foreign contingent. This time around, Gregory has opted for firepower up front with the likes of Lithuanian forward Nerijus Valskis, Maltese striker André Schembri who will be assisted by Brazilian attacking midfielder Rafael Crivellaro and Romanian winger Dragoș Firțulescu.
"The foreigners have to be outstanding players around whom you build the team. Look at Bengaluru FC in particular with their strong foreign contingent and NorthEast United, who were a surprise package last season with the likes of Bartholomew Ogbeche and Fernando Gallego.
"Their overseas players played exceptionally well, especially the top four teams who all had outstanding goal scores last season. They won matches, sometimes out of nothing. Mumbai City, many times last season didn't have a great deal of possession and didn't dominate matches. But they won matches because in Tsonga they had somebody who could just win them a game from nowhere. We didn't have that."
Gregory did admit that Indian striker Jeje Lalpekhlua could miss the start of the season since he is still recovering from an injury but feels Schembre and Valskis have already shown plenty of promise during the pre-season.
"In Nerijus and Andre, I've got two players who have proven they have the answer (to goalscoring woes) in preseason. I think they have scored nine goals between them in pre-season. They've already shown that they have that ability to score. And Rafael is a good footballer who plays two-touch, quick football and has a good left-foot."
Gregory also has brought in a promising Indian winger in Lallianzuala Chhangte from Delhi Dynamos and the Englishman is expecting a lot from him.
"He can do things that some of our foreigners won't even be able to do. Really, he's got a sort of tremendous pace, tremendous ability, creativity and he can score. I'm very excited about his signing," added Gregory.
With a fresh look and fresh faces in the team, coupled with established players like Anirudh Thapa, Dhanpal Ganesh and the likes, John Gregory will be hoping to shake off the stigma of last season and climb back up to the peak from which his team had a rather ungraceful fall last season.
"We can't change nothing that has happened in the past. I think last season, I don't look at it as failure. I look at it as a lesson, a huge lesson. We won't allow it to go back there again for many, many reasons because it was much more enjoyable in the previous season than it was last year. And, you really have to learn from your mistakes."