England's problem child has grown up.
The kid who was sent home from a Lions tour, the kid who missed a World T20 after smashing his hand on a locker has matured - or, at least, is well on the way to maturing - into the player his talent promised he might be. In Ben Stokes, England have a gem.
There will be those who look at the scorecard of this match, shrug and say: "But it was only Bangladesh."
And it is true that there were moments - such as during their first innings collapse - when Bangladesh's lack of experience in Test cricket was obvious. England's record against them - they have, to date, won all eight of the Tests they have played against one another - hardly reflects the narrowing gap between these two sides.
But in these conditions, the margin is not very big at all. And in this game, it has been defined by Stokes. Having produced an outstanding spell of bowling to help take Bangladesh's last six wickets for the addition of just 27 runs, he then contributed perhaps the most mature innings of his Test career to date.
True, he didn't turn it into a century. And true, it wasn't as eye-catching or awe-inspiring as his centuries at Perth, Lord's or Cape Town.
But while all those surfaces offered, to greater or lesser degree, the pace and bounce on which Stokes naturally feasts, this innings was compiled in conditions in which he has often struggled.
"We knew Stokes had talent: we knew he was strong; that he could thrash sixes and bowl bouncers. But he hasn't always looked an intelligent, adaptable cricketer"
Slow, low and offering help to the spinners, it was the sort of surface on which Stokes has often thrashed like a drowning man and given it away in infuriating fashion. Remember the dismissals in Grenada and Abu Dhabi: caught on the mid-wicket fence. Or the dismissals in Antigua or Abu Dhabi: charging down the pitch in desperation and missing.
Bangladesh tried to entice him into similar mistakes here. But where once he would have tried to thrash his way to a decent score, here he played like a Test batsman. Where once he had no confidence in his defensive technique, here he gave himself a chance to succeed by playing himself in, defending when necessary, rotating the strike and still putting away the poor ball with that brutal power that has become customary.
There were three sixes in this innings, but he no longer has boundary options alone; he has the ability, the technique and temperament to build an innings. Not satisfied with being a middle-order biffer - the sort of role that some, like Shahid Afridi, settled into a little too readily - he has combined his talent with an impressive determination to work hard and keep improving. He is well on his way to being England's best all-rounder since Ian Botham.
There will be those who point to his averages - the batting average is under 35; the bowling average over - and wonder what all the fuss is about. But if you judge everything on averages, you make some very average judgments.
Stokes is a cricketer who, with bat, ball and in the field, is capable of altering games in circumstances where few can. Each one of his Test centuries might reasonably be described as "great;" he has taken some catches - remember Trent Bridge, 2015 - that few could and his bowling here defied a slow pitch to change the course of this game.
In brutal conditions in which other seamers operated in three (or even one) over spells, Stokes started the day with a six-over spell of sustained skill and hostility. On a surface on which other seamers struggled to get the ball above hip height, he had batsmen jumping and sparring. And in an environment in which other seamers had to be content with cutters and slower balls, he swung the ball sharply.
With his strength, his skill and his determination, he has developed into a huge asset to England as a bowler. If he couldn't bat to save his life, Stokes may still be an international cricketer.
Some aspects of this will be of no surprise. We knew Stokes had talent: we knew he was strong; that he could thrash sixes and bowl bouncers. But he hasn't always looked an intelligent, adaptable cricketer. He hasn't always had the subtlety to complement his raw ability. But now that he has the skill to harness the reverse swing and now that he is learning to adapt to the slow surfaces on which he will probably have to play half his career, he is developing into something quite special.
England missed him when he was injured. It wasn't just his on-field influence, either. The team management felt the dressing-room environment at The Oval, when Pakistan defeated them to level the Test series, was a little too quiet; a little too passive. Stokes' belief, energy and determination play a huge part in driving this team forward.
As Paul Farbrace said a couple of weeks ago: "Stokes is a leader, wherever he goes, people want to go with him. He's loved being vice-captain on this tour. But vice-captain or not, he is a leader, and people follow him and want to know where he is going, whether he's going out for dinner, when he's practising."
The England management deserve some credit here. For many months now, they have done everything they can to make Stokes feel valued and appreciated.
It would have been perfectly reasonable to demote him to No. 7 in the order here or to leave him out of the limited-overs sides. Instead they given him responsibility - he was vice-captain of the ODI side on this tour - and security in his roles. Knowing his value and seeing his potential, they have invested heavily in him. Aged 25, he should be able to repay them for several years.
Don't discount that New Zealand influence, either. His father, Ged Stokes, was a rugby league player and coach who famously had a finger amputated when he couldn't wait for it to recover from a bad break. The son has inherited the father's determination and spirit.
There's more than a little Brendon McCullum about the way he lifts this England team: he might have made a decent All Black had he stayed in New Zealand.
None of this disguises the fact that England's top-order failed again. Again and again over the last couple of years, England's middle-order has rescued them after poor starts. While their sixth-wicket averages 83 in 2016, their next-best partnership is 53 for the seventh-wicket. That is fine, up to a point. But if England are to beat they best, if they are to win in Australia or in India, they will need the top-order to contribute far more often.
This game isn't won yet, either. What we have learned so far in this match is that, after the first 30 overs or so, the ball becomes quite soft and the slow pace of the wicket partially negates the turn on offer. Bangladesh scored 331 in the fourth innings here against England in 2010 and lost, while New Zealand scored 317 for 7 to win in the fourth innings here in 2008.
As a result, spinners are more dangerous with the new ball, when some deliveries turn sharply and others skid on, and seamers come into their own only if they can find some reverse. In that regard, England are well-served with Stokes. He has enjoyed an outstanding 24 hours or so, but his work is not yet done.