Without looking tell me who these people are:
Gary Tranquil
John Donovan
Don Treadwell
Mike Sanford
Irrelevant to the topic at hand, I can assure you.
The circumstances Ash walked into gave him a small window. He immediately capitalized on it with early recruiting, waving the banner of "big changes, strong pedigree"... and he brought in a "young and up and coming" staff.
One of his boom/bust hires was Mehringer, who had no particular resume to look at when he was hired. For a defensive coach who has never coached the offensive side of the ball and never called offensive plays, it was a massive risk - he didn't have the chops to step in and take over if things went off the rails. He compounded the risk by not bringing in any "mentor" figure as another offensive assistant, who could either help guide DM or even take over the reins if things went south.
If Mehringer worked out, Ash would have looked like a genius... but it was an extreme long shot. For a brand new head coach, it was a massive risk that he was essentially banking his career on.
It failed spectacularly.
DM was clearly way out of his depth. He force fit a team without a stable of WRs, without a proven mobile QB, and with questionable OLine depth into a system that went 4-5 wide, required a mobile quarterback, and required the OLine to give protection without help from a TE or FB. And he wanted them to move at break neck speed.
When that fell on its face, and his only WR threat went out with injury... he never adapted. Even after a 78-0 buzzsaw, he kept on forcing personnel into a system that they didn't fit.
Result: Multiple on-field embarrassments, and a promising recruiting class that didn't pick up another top recruit after the first kickoff.
So, the 2017 class could have been much stronger, but wasn't. Everyone paying attention knew that 2018 was going to be an uphill climb in NJ to get any of the top players, and the 2016 on field performance put us firmly off the radar for any who may have been on the fence. Switching OCs made the offense again start over with new plays, new formations, new personnel, which put 2017 in a hole right out of the gate.
When 2018 rolls around with its "easier" schedule, we'll have had two 40-60th ranked recruiting classes to stock the bare cupboard... in a season we need at least 5 wins.
The window isn't closed, per se.... but Ash definitely stumbled out of the gate in a way that Pikiell didn't.