The change in Merson's personal circumstances during 21 months of abstinent recovery from addiction to alcohol, gambling and cocaine has been well- documented. Less so the change in Merson's playing persona and performances which have prompted his recall to the England squad for Wednesday's World Cup qualifying match against Poland at Wembley.
"Yes I remember that time against Chelsea," says Merson, who went on to score the goal just before half-time that inspired Arsenal to rally to 3-2 before conceding a last-minute equaliser. "I just tried to calm the lads down, because we were all over the place, me included." Compare and contrast with two years ago.
"Then I would have drifted out to the wing and thought `Get out of this, we are going to get a good hiding here'. That's where I have changed, because I never used to get involved. I was having such a nightmare myself, I couldn't really tell anybody else what to do, could I? Now I have the confidence and belief to do it."
Not just those intangible qualities either. The addictive illness did its worst to conceal, then steal, his intuitive attacking skills - the close control, the vision, the passing, the eye for goal - and render him at times dervish, other times sloth. So far this season, however, they have re-emerged sharper than ever. His leaner but stronger frame now does justice to his appreciation of space and angles.
"Maybe I would have seen the passes two or three years ago but I didn't have the belief to try them," he says. "If I had given the ball away three times in a row, I'd have gone for the glory ball through the eye of a needle. Now I have grown up and I'm shrewder. I'll play the five-yard pass to get back in the groove then try the penetrating ball with my eye back in."
"I seem to be on a roll and I do wonder now and then how long it will last," he adds, "but at the moment I am just letting it happen. I always used to worry about whether I would have a good game. All I do now is give 100 per cent. At least I can come off the pitch with no regrets. Many times I would come off the pitch and think, `Could have done more.'"
Indeed these days he is usually the last one off, still applauding fans applauding him. "Sometimes I am asking the referee `How long?' and I would rather keep on playing even if we are winning by the odd goal," he says. "It's a good feeling. Before, I couldn't wait to get in and have a can in the dressing-room."
Merson was awarded his England debut by Graham Taylor - "I liked him; he gave me my chance" - as a substitute against Germany in 1991. Later that season he scored on his first full appearance, against Czechoslovakia in a 2-2 draw, but from then on it became a tale of under-achievement, "always inches away".
Against Holland in that World Cup heart-breaker of 1993 in Rotterdam, he hit the post. Worried by a thigh muscle strain, he was also in the "mad groove" of his addictions that left him thinking that feeling this debilitated way was normal. That summer in Detroit against the Germans he had also hit the crossbar from 35 yards.
It was on the United States mini-tour that Taylor ventured to suggest that Merson needed a pint to be placed in the penalty box to encourage him to get in there. "It was funny, I loved it," Merson recalls. "I thought, `I've made it. I'm a big drinker with the England boys as well.'"
When Terry Venables took over in early 1994, Merson was in his first training squad. "I was gone. My head was all over the place, filled with a million things," he says. "It was a shame. If you ask me now how he wanted to play, I couldn't tell you."
Venables hoped Merson would fill the left-sided midfield position that was to give so much trouble. He played against Greece, the 5-0 win covering up his own performance. "I had a nightmare," he admits. "It is a bad excuse to say I couldn't play the system because it's not the system, it's the player." He thought it would be his last cap; 14 of them so far, eight as a substitute.
"I used to shit myself when I went with England. I used to think, `I'm not good enough, I shouldn't be here'. I would have a laugh at dinner to mix in but in training I would just do enough, wouldn't try anything in case everyone thought I was a king twat. It was a self-esteem thing, always worrying about what other people thought about me.
"I understand the game more now, I've got more knowledge. Before, I wasn't really interested in tactics. I think I have a longer attention span and could go and play in someone else's position because I listen when they are getting coached as well. I don't switch off any more."
He should have no trouble in following the dietary regime of Glenn Hoddle and, at Arsenal, Arsene Wenger. In the mad old days, Merson would train on an empty stomach and "pig out" in the evenings. After a hearty meal, there would be six bags of crisps and eight cans of Guinness, having convinced his wife Lorraine that the club had recommended he increase his iron intake. If peckish later, he would send out for Chinese food. "It was embarrassing. I looked like I was pregnant."
Now it is cereal or toast for breakfast, pasta for lunch and chicken or meat and two veg in the evening with a couple of Lucozades and no snacking. His weight is 12st 10lb from 13st 12lb.
"I was carrying the equivalent of eight bags of sugar around the football field," he points out. He thinks he might now, at 28, be able to play until he is 35, if not at the highest level. He once thought he would be dead by 30.
"Before, if any ball went past me it was pointless me chasing it. It was a joke how I survived. I must have had some good players around me. You can't expect to play well if you are out of shape, especially these days with the game getting quicker by the year, and you have to be fitter.
"The prime example of the difference was against Sheffield Wednesday when I got my toe in ahead of Des Walker running for goal. I had the confidence and speed to take him on for the penalty. Two years ago I wouldn't have got near him, wouldn't even have tried. I am also stronger. I have done a lot of work with weights on my upper body." Since returning in February of last year, he has played more than 80 games consecutively for Arsenal.
Merson may not find himself in Hoddle's starting line-up on Wednesday but his versatility makes him an attractive substitute at least. "I'm one of the 23 best players in England. That's big enough for me," he says.
"Being in the squad in the past didn't really mean what it should have to me. Now this is bigger than anything before for me. I feel as proud as when I was PFA Young Player of the Year. This is a new start and I'm going to enjoy myself, not shrink into the background. It's my life."