For Blackwell's future at Bramall Lane now rests in the hands of the club's supporters and whether they understand and accept his excuses for missing out on the play-offs.
Make no mistake, if public patience snaps it will put intense pressure on the board for change and, given the growing importance of season-ticket sales, that pressure will be hard to resist.
Yet if results over the next six games pacify the doubters, Blackwell will be on far safer ground.
One game already has the potential to be a make-or-break fixture.
Blackwell may mark it down in his diary as 'Judgment Day' – Sunday, April 18 – the day of the Steel City derby.
Victory on Sheffield Wednesday's home turf would help Blades supporters forget many other disappointments. Some even prefer three points at Hillsborough to winning promotion. Defeat, of course, would be unacceptable.
The jeers that echoed around Bramall Lane after Sunday's defeat to Scunthorpe United will have haunted Blackwell over the last few days.
After last night's fixture between play-off rivals Cardiff City and Leicester City, the Blades are sitting seven points adrift of the top six. Bridging a gap of that size at this stage of the season is a massive task.
A quick look at the Blades' line-up against Scunthorpe highlights the extent of the club's woes.
Missing eight injured players and featuring four loan signings, only Nick Montgomery and Stephen Quinn were survivors from the team beaten by Burnley in last season's Wembley play-off final.
The Blades have raised around 13m by selling Kyle Naughton, Kyle Walker, Matt Kilgallon, Brian Howard, Leigh Bromby and David Cotterill yet less than half that amount has been re-invested in the team.
Loan players have arrived with extraordinary regularity to patch up the side – providing short-term cover but no long-term stability. A staggering 37 different players have appeared for the Blades this season, including 22 debutants.
Of course, there are two ways of looking at these statistics. While they confirm the difficulties the manager has faced in choosing an unchanged side due to injuries, it also shows that the Blades have been happy to fund short-term signings.
Blackwell is afforded a luxury that other managers, for example Sheffield Wednesday's Alan Irvine, can only dream about.
The Owls have used 23 players this season but budget limitations prevented the acquisition of loan signings even when injuries took hold and the need was apparent. Unfortunately for Blackwell, the expectation levels at Bramall Lane are far greater than across the city.
And why shouldn't Blades fans feel confident about the state of things when money is available to invest in foreign clubs, build hotels on the club car park, and develop a state of the art youth academy?
Chairman Kevin McCabe feels justifiably proud of the club's progress off the field during the last decade but key mistakes have resulted in backward steps.
Former manager Neil Warnock failed to keep the club in the top flight, the appointment of Bryan Robson was misguided, and home-grown youngsters have been in short supply.
At least Blackwell's return to the club, after spells with Leeds United and Luton Town, stopped the rot and so nearly resulted in a return to the Premier League.
In times of turmoil, a manager is always the first in the firing line – but Blades supporters should not forget that these are difficult days for a lot of clubs in English football.
Blackwell, who is under contract until summer 2012, first expressed fears about impending chaos 12 months ago knowing that the Blades would be making considerable cutbacks during a third season outside the top flight.
After losing to Burnley last May, he offered to quit but was persuaded to stay on by McCabe amid interest from Queens Park Rangers.
Financially, football now appears to be in the eye of the storm and those who have battened down the hatches will be among the first to move forward when the dark clouds pass.
The Blades have only a few players under contract for next season which brings an ideal opportunity to reshape the squad and regain stability. The appointment of John Pemberton as Academy manager is designed to improve the quality of the club's youngsters.
Blackwell argues that any manager or coach would have found it hard to win promotion with Sheffield United this season. The important question now is whether supporters agree.