The NFL says it is upset with changes Nielsen plans to make to its television audience measurement methodology for the upcoming season. The league calls the changes “rushed” and says they could have a negative impact on sports viewership reporting.

Nielsen announced that it will begin implementing the new measurement approach on Aug. 31. The updates include changes to how Nielsen determines when multiple people are watching the same event at the same time. The NFL is coming off what it describes as a particularly strong period for television performance after Nielsen began using its “Big Data + Panel” approach for all events last September.

While both outlets focus on the NFL’s criticism of the timing and potential effects of the updates, the reporting centers on the same core dispute: how Nielsen’s revised measurement method may affect sports ratings and comparisons to prior results.