Keith Curle, May 2015: "I know people in Carlisle don't like change." The irony, three years on, is that it is the Blues doing the changing. The man who wanted to transform United is now a victim of restless urges, this time in the boardroom.

Ignore some of the pretence that this is a smooth parting. Whatever is said publicly about Curle's imminent farewell, this had become an awkward marriage, one hand no longer holding the other.

For two more games, Curle will continue to show a professional face to the world. United, who have struggled to stay afloat in the tide of opinion on this decision, clearly did not want to do anything so vulgar as sack the boss.

All, though, was not well. Once it emerged Curle's contract was winding down, it was plain directors saw no rush to renew it. Dealt with in due course was the line. Not now. Certainly not urgently. Faith, blatantly, was on the wane.

The same might be said the other way. There were times, to borrow a memorable Curle phrase, when he treated Carlisle's owners and directors with lipstick, but others when he must have been itching to reach for the brick.

Those fond of the 54-year-old - and there are many, clearly - feel he deserves sympathy for trying to drag the club into a more professional age, in spite of its rust, cobwebs and achingly slow ways. They feel he gave the Blues their best shot at glory for years.

His critics (and there are plenty of those, too) feel this image is too shiny, and that Curle had more than enough money, and opportunities, to deliver success, and a mid-table finish in League Two is not good enough in that context.

Take your pick. For all he said about building "pillars and foundations", there was always someone ready to whisper differently. There were times, over the last four years, when you could have papered Brunton Park's walls with agendas.

On this basis you could argue that Curle, ultimately, failed to unite the club. Yet maybe that was never his job, and Carlisle always needed someone to shake it up, upset people, drive contented failure away.

To a significant extent he did that. His routing of a slack squad in his first campaign was impressive. Delivering safety, his initial brief, was completed a few months after the worrying decline under Graham Kavanagh and the latter days of Greg Abbott.

At times, to start with, Curle appeared at pains to demonstrate a new sheriff was around. The ostracising of Gary Dicker and Billy Paynter attracted the attention of the Professional Footballers' Association - it was poetic when those two then scored against Plymouth to secure survival - while certain staff, first-team and academy, were irritated by his style.

Generally, though, it was a dressing-room ripe for a wrecking-ball. Danny Grainger and Kyle Dempsey were rightly identified as characters Curle could build around, but others were cast away. In the market there were misses and hits, as there were throughout, but history is kind to the calls that mattered. Chasing Alex Marrow. Summoning Derek Asamoah. Buying Charlie Wyke. Loaning Jason Kennedy. Recognising that even Steven Rigg, previously of the Northern League, had grit that was lacking elsewhere.

He also made an impression in other ways. Declaring that he had unearthed a 1970s tactics sheet from his office fit his new-broom image. His interviews, meanwhile, were routinely colourful, and while one wondered what the squad made of being accused of lacking "male genitalia" after an atrocious defeat at Accrington, that outburst also worked.

It was the following summer, unshackled by relegation fears, when he became more progressive, and signed what Abbott used to call "hardened criminals" - Michael Raynes, Luke Joyce, Jabo Ibehre - to give a transitional team ballast.

Ibehre was a masterstroke. Curle pushed more of the journeyman Londoner's buttons than any other manager. Carlisle were not quite good enough for a play-off challenge but 2015/16's team had character, and characters. Their display at Liverpool, in an epic League Cup tie, was magnificent. It said United could play again with ambition and confidence. That they lost at home to winless Newport in their next league game reminded us of the distance still to go.

There were also "distractions", as Curle called them, on the road to 10th. The "billionaire" investment farce proved the club was still dysfunctional, while the Storm Desmond floods were a grievous test for club and community. Curle's players - and the club's staff - did their part in the latter extremely well.

What he made of the ownership overall will probably have to wait for the book, but even early on, one chief, John Nixon, bizarrely told a BBC documentary fronted by Sol Campbell that he hadn't realised Curle was black before interviewing him. After a victory at Stevenage, Andrew Jenkins swore at the media. Steven Pattison had also by then allegedly told fans "not to come back" if they didn't like the fayre and then a vice-president and sponsor (Andy Bell) was forced to resign after controversial Twitter remarks about the Hillsborough disaster. Whatever one thought of the relevant debates, nobody could say the Blues were advancing in complete harmony.

Curle's focus, though, remained. Next, given extra "football fortune" from cup ties and player sales, he tried to build a promotion squad full of proven winners: Nicky Adams, Mike Jones et al.

It so nearly worked. With Wyke maturing, Kennedy scoring, Adams bringing outstanding creativity and even Joyce providing a wonder goal (against Crawley), Carlisle became irresistible that autumn. Curle was the club's first manager of the month for eight years. The transformation from the dog days of 2014 seemed complete.

That team will remain in the memory even though it then fell. Bradford's triggering of a clause in Wyke's contract, plus injuries to Grainger and Jones, exposed the team. There was not enough in reserve and goals were shipped too readily. Curle tried to wheel and deal, fans also responding with a transfer crowdfunding effort, but the mid-season influx was poor - and in some cases (Joe Ward, James Hooper, et al) barely explicable.

After a record unbeaten start, there was a seven-game scoreless run. Curle, at this stage, claimed that some in the club still wanted him to fail. United salvaged a play-off place but were weaker than Exeter, however agonising their semi-final defeat.

After that missed opportunity, Curle called the club out on its "ambition". A tumbleweed summer of news followed. Eventually signings trickled in but Carlisle did not start 2017/18 well. Yet they were still "overachieving", according to Curle, on a budget directors protested was the equal of the previous year.

With these mixed messages, one could sense cracks opening. Adams' knee injury was untimely but Carlisle had other limitations. They were no longer fluent or confident, especially at home, and one had to be thankful the manager's relationship with Clint Hill was so strong that the 39-year-old chose to sign up for the struggle from September.

The veteran added steel, and United again flirted with the play-offs, though never convincingly. Belatedly, Curle unlocked Jamie Devitt's qualities, was vindicated on Gary Liddle and rediscovered faith in Mark Ellis, but a reshaped strikeforce was seldom deadly enough.

This season's other main curse has been a failure to beat the higher fliers. It placed Carlisle too near the middle for excitement to grow. For this, any coach and tactician must answer. Curle deserved better, though, in other respects.

Prominent out-of-work managers being handed tickets to the directors' box was not a good look when everyone knew his future was uncertain. In terms of the general operation, fan complaints about bird mess on seats and catering flaws, for instance, kept discontent bubbling, while United's financial status remains a more profound concern. Many felt that, at a recent fans' forum, it was rich for Curle to be thrown under the bus over spending by those who sanctioned it.

Curle, that night, also had to live with a co-owner blurting out an injured player's wage, another saying confrontational things about old investment sagas, and the third "custodian" absent, on supposedly higher football business. Without Nigel Clibbens' attempts to paint a more detailed picture, United's image at top level would be even worse.

Those troubles will remain once he's gone. After the allegation he did not care for the club's youth players (he would argue they were not good enough), United will need to oversee better results there. Their apparent wish to be more nurturing, rather than buying talent in, will need a plan, skilfully applied. Patience will be thin if the first-team flounders. Calamity awaits if priorities are askew.

Ideally, the next manager will talk a good game as well as play one. The Blues are short of salespeople, other than an overworked few. In the media room, Curle was affable and humorous. With microphones on or off, he would treat you as an equal. On the record, some of his meanderings were extraordinary (comparing a criticised team to a "missus" being called a "minger" by hoodlums, say), but he rarely displayed grudges, or refused to engage.

His appearances on TV and in the national press were interpreted as self-promotion by some, yet his persona inspired devotion. He is surely the first United manager to have his face tattooed onto a supporter's body - and certainly the first whose name was immortalised in adapted Peter Andre lyrics ("Mysterious Curle").

Helping the handover, by assisting with player contract decisions, will also help show a diplomatic side: another tick for admiring chairmen, perhaps. No doubt he will reappear somewhere soon. His CV did not, in the end, acquire its first managerial promotion at Carlisle, but it had longevity, and a general record of improvement, with no obvious stain.

The best tribute, probably, is that Curle's teams were hardly ever a soft touch: a transformation Carlisle sorely needed. Someone else will now have to add promotion-winning flair, and pace, on a reduced budget and with scepticism still hanging heavily over the regime.

The agent of change became a victim of it in the end. We may need a stiff drink, though, before United's next revamp.