I don't think those stats on their own represent a trend of any kind, for various reasons.
- First of all, they don't take into account strength of schedule, which definitely affects the chances of a team winning a game.
- Second, dividing it by quarters is a bit arbitrary, why not fifths or thirds? I understand that it's easier that way, but we might different results by dividing the schedule on a different way.
- Third, the sample size is still too small for each quarter. Imagine we would have done this on the first two years we could have said, "the Jets are decent finishers!". Or just the last two, "the team was too veteran and crumbled in the end (as you said)". It's just too arbitrary.
- Fourth, they don't take into account injuries or the strengh of the Jets' roster for any given year.
It's a nice effort of analysing but I don't think it means much more than a source of good talking points.