There are more reasons too, one of them being some of those teams do not spend to near the cap ceiling even as their rebuilds progressed, which could be seen as a competitive disadvantage, similar to a team who would be using cap space on players who are no longer on the team. I wonder what other spending constraint those teams may have, scouting, management, coaching?
Given that 5 of those 7 rebuilds that are given as examples of struggling also rank in the bottom 9 in cap space used, perhaps there is something to financials playing a part in a successful rebuild?
The Jets are an interesting study since up until this year they would have likely been included in the struggling rebuild category, since 2011, once they moved, they have drafted in the first round at #2, 17, 9, 13, 9, 7, and last draft 24. It took them about 6 years, they did not try to take, or were unable to take too many shortcuts, but they look to be on the rise finally even as one of the lesser spending teams.