Stephen Constantine continues to be a polarising figure in Indian football Ulrik Pedersen/Action Plus via Getty Images

Minutes after India's biggest win in the history of the Asian Cup - a 4-1 dismantling of Thailand that few would have predicted - the players were mingling with the few Indian and international journalists on their way to the team bus.

The head coach Stephen Constantine was giving vent to his feelings about some of the criticism that has come his way in recent months, especially about his team selections and tactics.

"You guys have your own opinions, and I don't have a problem with that. But when you start criticising players that I have put in, or second-guessing my opinion, you know, it's just wrong," he said. "Some of the crap that you have been saying about me, the team, about some of the players. It's just nonsense. You've just got to let somebody get on with the work."

Constantine's relationship with the media and the fans has been a prickly one at times, perhaps best described as a mutual lack of appreciation. Even in Abu Dhabi, he has remained elusive for interviews, and has been selective with allowing access to his players.

A lot of it perhaps stems from stories about rifts within the dressing room, or the lack of certainty about his future with the Indian team after the Asian Cup, which have made the rounds of Indian media but have been denied by everybody associated with the team.

How is it that even after everything he has achieved, Constantine doesn't get the credit he deserves? Has India's rise in recent times been down to his tactical acumen, or good fortune, or perhaps a bit of both?

Constantine's India connection

London-born Constantine's arrival in January 2015 was his second stint as coach of India, having first taken charge in 2002. Constantine, who is an ardent Arsenal supporter and often tweets in support of his favourite club, came to India after a stint with Nepal.

The Asian Cup qualification now is definitely Constantine's greatest achievement with India, and perhaps the biggest stage he has taken any national team to. In 2002, he had taken an India U-23 team to victory in a six-team LG Cup in Vietnam, but that was an invitational tournament, with an Indonesian club participating alongside India and four other U-23 teams from south-east Asia.

What swung the India job the second time around in his favour was a 66-place rise in rankings that he helped Rwanda achieve in his previous assignment. Shades of that have been visible in how India have gone up from 173rd when he took over in early 2015, to 97th going into the Asian Cup, something that is likely to improve further, especially after the Thailand result.

It's often about structure

India have made giant strides forward in recent years Ulrik Pedersen/Action Plus via Getty Images

When talking about the upturn in fortunes for the Indian team, Sunil Chhetri points to the World Cup qualifier against Guam in Bengaluru in November 2015 as a turning point.

Speaking to ESPN before the start of the Asian Cup, centre-back Arnab Mondal had credited Constantine for reinforcing the importance of that match. India, who had lost five matches on the bounce, had to win to get a good pot for their qualifying group playoff, while Guam were coming off wins against India, Turkmenistan and a goalless draw with Oman.

"Guam are a very good team. They are physically very strong, and our first target was not to concede a goal," says Mondal of a game where striker Robin Singh scored early. "We played knowing that we have to defend well and then counter properly - that was our strategy. The last 55 minutes or so we played with a man down [central midfielder Sehnaj Singh was sent off] and we really had to fight."

It's a formula that India have perfected since -- Chhetri, goalkeeper Gurpreet Sandhu and Constantine himself have spoken about how difficult it is to play against this team. Critics might add it can sometimes make India difficult to watch, but it is the way that the coach has laid out for the side to play.

"Look, we try to attack in every game. We have been playing teams like China, Oman and Jordan, and when you play teams of that quality, it can be difficult to impose your will," Constantine had said ahead of the Thailand game. "We're not going to change how we play."

Also see: 'It's not for the Indian team, it's for the whole of India'

A dash of belief

Both Constantine and Sandhu compared the biggest evolution in the team since 2015 being in the belief within, and the overall work rate of the squad. Gouramangi Singh, who played the 2011 Asian Cup under Bob Houghton, remembers Constantine having instilled similar belief in him when he was picked up as a teenager to train with the senior team while still with the Tata Football Academy (TFA) in 2003-04.

"When we were together as a team, the belief itself was that we are playing a good team, and there was never talk of winning matches. It was considered a huge thing to draw or even lose by a respectable margin," says Gouramangi.

"The first change of mentality came with Stephen Constantine. When I travelled with the senior team for the first time, it was with Constantine, the words itself were, 'You guys should believe that you are as good as any of those boys. There's nothing to fear, and it is just a game of football, and you have to be prepared for 90 minutes.'"

The question of selection

Ulrik Pedersen/Action Plus via Getty Image

One of the more innocuous criticisms of Constantine has been about his rotation of captaincy, but the biggest questions have been about ignoring players like Rahul Bheke, Jobby Justin, or the injured Michael Soosairaj from the national setup.

Mondal defended his former coach in this regard.

"If you look at coaches all across the world, each has his own set of beliefs, and so does Constantine. He must have analysed the players at his disposal and decided that there are specific strengths of the players he has and he needs to play to that. He has only called up players who he finds useful for his system."

While it is not unusual for fans and the media to question a coach's selection, what sticks out is how sensitive Constantine appears to be to any such criticism. Members of the media say Constantine keeps a tab on everything that is written and said about the Indian team, and remembers every bit of negative press.

"I pick players that are going to work. If they can't work or won't work, they are not here. It's not a vent, but I needed to get this out of my system," Constantine said after the Thailand game, which might have given him some closure.

Also see: Buoyant India announce themselves to Asian elite

Backing youngsters to the hilt

Gouramangi remembers Constantine surprising him by picking from out of TFA, just as the academy was closing for a summer break in 2003, for the U-19 invitational Milk Cup in England. At the camp in Goa ahead of the tournament, Gouramangi recalls Constantine being a hard taskmaster, a reputation that stays with him to this day.

"I wasn't even that technically sound. We used to be anxious if we could keep up. There was the team announcement in a ground in Goa, and this coach after the last training session, called me to the side, and usually that's never for good news. He might say you are not travelling. He simply asked me, 'listen, do you think you can lead the team?'

"I said, 'of course!' That was an important part of my growing up. He would support young players. Not just me, every youngster feels valued. They can become better and do good things in future."

You can see that in the present team with Constantine's handling of players like Anirudh Thapa and Ashique Kuruniyan, both of whom were key in India's win against Thailand. Thapa improved his performance in the second half, and said later how the coach had pointed out to both him and Pronay Halder, his partner in central midfield, how they were getting drawn wide by the Thailand midfield.

Constantine also gambled by fielding Ashique as striker, alongside Chhetri, and he responded with a top-notch performance. Constantine would explain later that he wanted to use Ashique's physicality and pace because he backed his ability to stretch the Thai defence.

A touch of luck

Comparisons with the 2011 Asian Cup campaign will be inevitable, especially after India have begun the 2019 edition with a victory. It must be remembered, though, that India were drawn then alongside South Korea, Australia and Bahrain. Two of those teams were coming in on the back of World Cup appearances, while the third had lost by a goal to New Zealand in the playoffs for South Africa.

While India have been more fortunate with drawing UAE, Thailand and Bahrain, they still have some work to do to navigate this group and make the round of 16, which is what Constantine has set as the primary target. According to Sandhu, there's a special unity and fighting spirit in this group, that the coach has been able to foster.

"The kind of belief that we have built over the last four years is something that we are proud of, and we have been working really hard," he says. "It's a special feeling when you play for the national team. I think over the last four years, we as players have recognised that, to embrace that, and to make sure that we give everything when we step on the pitch."

With the Thailand win, Constantine's India have set themselves on course to cap off what the coach calls the "best time we've had in a very, very, long time".

It should also put his name down in Indian football history as a coach who made a significant difference to the team's fortunes.