England had to toil desperately hard to finish off the Australian innings: 130 overs of probing, disciplined bowling; 130 overs of wonderfully committed fielding; 130 overs of applied thought and planning. There are probably more talented attacks in world cricket, but you really couldn't ask for much more than England offered in the field here.
The reason they were, in part at least, thwarted was the excellence of Steven Smith. England tried everything short of a tethered goat to tempt him into a rash shot, but he was having none of it. Knowing that his wicket probably represented the difference between the sides in this game, he demonstrated wonderful patience and desire in recording the slowest Test century by an Australian batsman this decade.
It was, in its way, a great innings. And a reminder of one of the great truisms of cricket: it's not just the shots you play that make you a good batsman; it's the shots you don't.
With England having had to work so hard for their rewards - and having just witnessed an example of how to conquer such conditions - you would think they would sell their wickets equally dearly. And that was encouraging. For in Cook, England had one of the most obdurate, disciplined and determined batsmen they have ever possessed. Really, if you were looking through England's Test history for a batsman to survive an hour in such conditions, Cook's name would warrant consideration.
Or at least it would have done. At present, though, he looks worryingly fragile. Dismissed by a full ball in the first innings - it was a lovely delivery, but opening batsmen really do receive quite a few such deliveries - he showed fragility against the short ball in the second.
This dismissal was a sucker punch. Attempting a hook - a completely unnecessary stroke in the circumstances - he top-edged the ball to long leg. Unlucky? Maybe; it certainly took a fine catch to dismiss him. But there's a reason the fielder was positioned there and it was a stroke that Smith chose not to play on many occasions.
It was an oddly gullible shot for such an experienced player. A shot that would have made a passable impression of Andrew Hilditch, whose compulsion for the shot brought ridicule more than 30 years ago. A shot that makes you want to sell him double-glazing or send him an email purporting to be from a Nigerian prince asking for his help in transferring your fortune. A shot, undoubtedly, that Kevin Pietersen would have been criticised for playing.
Cook is human, of course. And humans make mistakes. Especially after 130 overs in the field. But, as a senior player in a line-up that includes three men with fewer than 10 Test caps in the top five, it is essential he sells his wicket dearly. Essential he is the one to blunt the attack when Australia have a new ball and an hour before stumps. Essential he leads the way. And here he gave it away.
"The worry is not that Cook's eye may have gone, but that just a bit of the hunger might have done"
The worry is not that Cook's eye may have gone - to use an old expression - but that just a bit of the hunger might have done. Maybe hunger is the wrong word. But does he still have the desire to dig as deep as he once did? Does he still have the uncluttered mind required to do so? Are the demons that dog many of the best batsmen towards the end - just ask Ricky Ponting or Jonathan Trott - starting to gather?
Eventually, after going to the well time after time in a bid to find the mental fortitude and concentration to succeed, batsmen tend to find it has dried. And if they lose even a fraction of a percentage of their drive, at this level, they find a pack of hungry, fit and ambitious fast bowlers ready to exploit the weakness.
It was a point made by Chris Rogers, the recently retired Australia batsmen, while commentating on ABC. "You can never write off a champion," Rogers said as he reflected on the dismissal. "But you have to question where he is mentally. It is a strength, the pull shot, but in this situation you probably don't want to try it.
"If that's a young player, you'd sit down with him as a coach and say, 'why did you do that?'. And because it's an older player like Cook you start to ask, 'why did you play that shot?'
"It's hard if you've been around forever to dig deep every series and fight."
Cook has been out hooking before, of course. Not often, but it has happened. And it didn't necessarily mean anything. In the second innings at Adelaide in 2013, for example, he fell to a top-edged hook off Mitchell Johnson and in the second innings at Trent Bridge, in July, he was defeated by a perfect bouncer from Chris Morris. Most opening batsmen will fall in such a manner at some stage and Cook's record against the short ball remains outstanding.
This felt a bit different, though. This felt less a reaction to a superb piece of bowling - though Josh Hazlewood's spell was terrific - but more the result of a somewhat scrambled mind. The result of a man who knows his game - defensively as much as his scoring options - is out of sorts and therefore snatches at any opportunity that comes along. It felt different.
Maybe this is an overreaction. If history has told us anything, it is that we should never write-off Cook. His record and his determination demand respect and patience.
We have only to go back to 2010 - a time when he looked every bit as out of sorts as he does now - to know that he can turn the corner quickly and dramatically. He has come back from worse runs than this and there is no doubt he will be given every opportunity to do so again. But he has now reached 50 just once in his 10 most recent Test innings (he went on to make a match-defining 243 on that occasion) and reached 100 once in his most recent 23. Is that still a blip? Maybe.
But it bears repeating that this is his seventh Ashes series and in just one of them has he averaged 40 or more. Indeed, only twice has he averaged above 30. The memories of his avalanche of runs in 2010-11 - when he made three centuries and averaged 127 - sometimes skew the reality of his long-term Ashes record. In the two other series he has played in Australia, he averaged at least 100 fewer.
There has been encouragement in the performances of England's less experienced batsmen in this match. But if England are to win the Ashes, they surely need Cook to contribute in a meaningful way at the top of the order. He has time to turn things round, but he looks - right now - worryingly short of his best.