This phrase seems obvious to some, incomprehensible to others. It means only what it says. It does not say that each ball is equally memorable, or equally thrilling, or equally interesting (or dull), or that each contestant plays each ball equally well (they don’t. Occasionally, even international players get a bad bounce and misfield a hard hit drive). It says that each ball is exactly equally competitively significant - that it contributes exactly equally to the result.
The score in each innings is the accumulation of the outcome of each delivery in the innings. None of the deliveries are left out under the Laws of Cricket, and none of the deliveries have more weight than any other deliveries. All are counted equally. There are three outcomes in the record for each ball - balls, runs and wickets. Whatever choice a player makes - whether it is to defend a ball (outcome 1 ball, 0 runs, 0 wickets assuming that the ball is successfully defended) or to hit a six (outcome 1 ball, 6 runs, 0 wickets, assuming that the six is successfully hit) - counts equally towards the score. Remember, the score is runs for wickets in balls.
Each delivery is exactly equally a resource. Regardless of how the batting or bowling side choose to use it, it gets used up.
It follows from this, that no single delivery or over in an ODI match is any more significant to the outcome of an ODI, than any other delivery or over. Some overs may be memorable, or thrilling. But they do not influence the result any more than any other delivery.
So, all propositions of the type “Team X lost because their batting pair A and B played bowler P badly in the 48th over” are incorrect. That 48th over only contributes 1% (6 out of 600) to the outcome, like the 45th over or the the 4th over.
The proposition that some over X in a match is more significant than any other over in the match is easily refuted. The significance of over X arises from the state of the match at the start of over X. It follows from this, that the overs leading up to over X must be at least as significant, since without them, the match would not reach the state it reached at the start of over X. So, by contradiction, X can’t be the most significant over in the match. It also follows from this that no delivery can be less competitively significant than any other. If we could ignore the outcome of a delivery leading up to the over X, we would not reach the state of the match at the start of the over X.
It is useful for cricket fans to see this, because this mistaken notion that over X is uniquely significant leads to awful things like players being abused, players mental capacities being doubted and all sorts of other similarly chauvinistic reactions.
It is necessary for cricket fans to see this, because this fiction about “crucial overs” arises out of an anxiety about the result. There are no crucial overs. And there are no trivial overs. All overs are equally crucial to the outcome - the ones which were played out quietly, and the ones in which risks were taken.
So, while it is tempting to think that an ODI is decided because Dhoni played the final over better than the opposition bowler, this is incorrect. The ODI is decided exactly equally because of the way each of the 600 balls in the ODI were contested. Each ball is exactly equally competitively significance. What matters to the outcome of an ODI is not what you and I can remember about it afterwards, but what was actually contested.
There are mind games all the time in an ODI, and these introduce nonlinearity
But doesn't the value of wicket change based on how many balls remain? If that's the case then wouldn't particular overs (in combination with in game situation) be higher leverage? Obviously, the over in it of itself doesn't out weigh any other, but the stakes of a particular over in a particular game changes based on things like wickets and run-rate. I guess what you're saying is that in terms of cause-effect each event prior was equally important in arriving at this moment, but particular moments themselves do seem to carry higher stakes especially when we add in that not all batters wickets are valued the same (getting out a very productive batter early in the game might have greater outcome than getting out a poor batter with 2 balls left in the innings)