There was a telling moment, about 140 overs into the India innings, when Jasprit Bumrah launched a delivery from Chris Woakes down the ground.
It wasn't just the sight of England's best bowler, in this match at least, being thrashed to the boundary by a man who came into this Test with a batting average of 4.81 that was revealing. It was also the fact James Anderson had to trot from his position at mid-on to fetch the ball.
Joe Root, at mid-off, had attempted to intercept it. But he appeared to slip and, for a moment, clenched his leg in pain. So it was left to Anderson, as it so often is, to make amends.
At that point, Anderson - the 39-year-old Anderson - had bowled 33 overs. Despite his age, despite the fact he has played in every Test in the series and despite the fact that England would like to include him in the final game, which starts in Manchester on Friday, he had bowled more overs in the innings than any of his colleagues.
Anderson had, by his own admission, tried everything to gain some lateral movement. He had tried to swing the ball and seam the ball. He had tried to bowl cutters and tried to find reverse. He had bowled from both ends. In the end he settled for simply attempting to bowl dry and build pressure that way. Woakes and Ollie Robinson had, more or less, come to the same conclusion.
The problem was, such a plan requires more than three bowlers to execute. And, at that stage of the innings, Craig Overton, the fourth seamer, had only bowled only 16 overs while Moeen Ali, the spinner, was conceding four-and-a-half an over. So Anderson, Woakes and Robinson were forced into spell after spell. Even when it became obvious, from their pained expressions and, in Robinson's case, diminishing pace, they had to bowl as, to put it bluntly, their captain appeared to lack confidence in his other options.
It was a passage of play which may well have consequences for the rest of the series. With the final Test starting on Friday, England will be loathe to press Anderson and Robinson, in particular, into service once again. They have already lost Jofra Archer for the T20 World Cup and Ashes. They have already lost Stuart Broad for the rest of this season. They really don't want to be in a position where they are taking risks with Anderson or Robinson. It was, perhaps, telling that neither emerged after tea on day four. The exact reasons for this are, at the time of writing, unclear. But it is far from impossible the team management simply said "enough".
"England have already lost Archer due to an injury which may have been caused by an excessive workload. They have to find a way to spread the load more evenly"
"We're all feeling it," Woakes said afterwards. "I think we have all bowled 45 overs plus in the game. Naturally, you're going to be a little bit sore. There are occasions in England where you can maybe bowl at about 90 percent but here you had to slam every ball into the pitch to get anything out of it. Naturally that takes it out of you, so there's a few sore bodies in the dressing room."
None of this reflects especially flatteringly on either Overton or Moeen. Overton had a really encouraging match in Leeds where the surface provided assistance for his brand of fast-medium seamers. But if he is going to be a viable option in Test cricket, it is on days like this he must earn his living. It is on days like this he must ease the burden on his celebrated colleague and fulfil the task of stock bowler with hours of grunt work. It was his job to bowl 35 overs for around 60 runs and ensure Anderson and co could be used in shorter, sharper bursts. But such was Overton's profligacy on day two - when he conceded four an over - Root seemed to have little faith in him.
Much the same could be said about Moeen. He passed Jim Laker's record for Test wickets during India's innings (only Graeme Swann, among English offspinners, has more) but it was not a day which enhanced his reputation. England desperately required control but Moeen, in conceding 4.53 an over, was unable to provide it. He claimed a couple of big wickets - he has now dismissed Virat Kohli six times in Test cricket - but also made a fearful hash of an important run-out opportunity, was involved in the decision to use (and squander) all three reviews and, by his own admission, brought India back into the game with his dismissal in England's first innings.
"When I was batting in the first innings, I felt we had them down a bit and I tried to hit a six and got out and that brought them back in a bit," he told Sky. "It was a crucial time."
Jack Leach may not offer Moeen's ceiling with the bat or ball. But he is reliable, worthy and, in his Test career to date, has never let England down. You wonder if Root might not have wished he was around a few times during the day.
In mitigation, it must be noted that India's bowlers found the pitch no less heartbreaking than England's. While there is just a little rough for the spinners to work with outside the left-handers' off stump, there is almost no other encouragement for bowlers. As Moeen put it, "if Bumrah comes in and hits Woakesy straight down the ground, it's a great wicket." Moeen also pointed out that he has hardly played red-ball cricket in recent months and that his action is "a little bit off". As he admitted: "I could have bowled better."
England have some lessons to learn here. They have already lost Archer due to an injury which may well have been caused by an excessive workload. They have to find a way to spread the load more evenly if others are not to follow.
It was said long ago that Anderson was a sports car being used to deliver scaffolding. These days he is a classic sports car being used to commute to work, ferry the kids to school, hired out for weddings and to deliver scaffolding. And remember, that second-innings bowling average in his 15 most recent Tests is now 60.57. In the same period, his first-innings bowling average is 17.87. Over such an extended sample size, those are statistics that cannot be ignored. The warning signs are there.
Still, all results are possible going into the last day. And there will be a sellout crowd at the Kia Oval on Monday for the fifth day in succession. It reflects well on this venue and this series. Test cricket faces many issues, many challenges. But the reason for sustained optimism is that we have a great game. Monday might just offer us something of a classic final day. Anderson will be hoping that, for once, England can get by without him being required a make a contribution.
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George Dobell is a senior correspondent at ESPNcricinfo