The deadline-day error that could yet prove a crucial moment in Sunderland's promotion push

Not because the players selected weren’t trusted, but because it represented a shift away from the template he’d employed in previous matches.

In the end, the result was emphatic, the feel-good factor on Wearside moving through another gear.

Nathan Broadhead excelled, and out to his left Aiden O’Brien delivered the kind of hard-running, intelligent display that has made him a hugely respected member of the group.

The game plan worked to perfection.

At face value, it also represented something of a fairly rapid revival.

After all, not even a month had passed since the Irishman was on the brink of leaving the club, albeit on loan.

Yet even as he nudged towards the exit door, his potential place as an important squad player was never in question.

Though the end to the season proved to be bitterly disappointing, Johnson did enjoy one impressive, extended run of positive results and O’Brien was integral to it.

The style was more direct then, and within that O’Brien earned the respect of fans, staff and team-mates alike for his selfless play, seen as crucial in Charlie Wyke’s outstanding run of goalscoring form.

The point being, there was never any scenario in which Johnson was going to try and move O’Brien on of his own accord this summer.

But a myriad of factors came together to make that last-minute move to Doncaster Rovers a strong possibility.

One is that Sunderland’s style has shifted this campaign.

The absence of Wyke has accelerated the move to a passing game, Ross Stewart’s mobility allowing and indeed requiring the introduction of another playmaker/number ten in most games. The results have been emphatic and Stewart’s goalscoring form has left O’Brien with little chance of usurping him.

It’s not that Johnson doesn’t see a role for O’Brien in a better footballing side, as such.

O'Brien is a good technician, particularly in build-up play, but it’s merely that Johnson believes he might be more of a threat playing off the left, as he used to do with great danger against his Bristol City sides at Millwall.

In that role he’s also a superb defensive support for his full-back.

Ideally, O’Brien sees himself as a nine and of course out wide, he is always going to find it difficult to edge past Aiden McGeady.

“I think he sees himself as a nine at times, and I probably see him more as a nine-and-a-half or an eleven cutting in from the left,” Johnson recently explained.

"When I played against him at Millwall, I always thought that his running power was really dangerous and difficult to deal with when he cut inside from the left.”

It was in this role that O’Brien starred against Blackpool, scoring a tremendous hat-trick in the Carabao Cup.

But when Leon Dajaku signed on loan from Union Berlin on deadline day, O’Brien was presented with yet another barrier to the first team.

With Will Grigg opting to join Rotherham United, despite a deal with Doncaster Rovers having been broadly agreed in the week previous, there was an obvious opening for O’Brien.

The chance not just to play regular football, but to do so as the spearhead of the side who would be looking to him to lead the line as their primary source of goals.

For Sunderland, there was then a balance.

Letting him go would potentially have weakened the group and left Johnson vulnerable to injury, but there was also a duty of care to the player whose gametime was very obviously under threat.

The decision was essentially left with the 28-year-old, who opted to pursue it. Remember that he is now in the last year of his current deal, with no guarantee of another. That he needs to be playing and impressing at this stage of his career, wherever that may be, is obvious.

In Doncaster there was consternation that the deal was not completed in time and ultimately it was uncontested that the issue was Sunderland not being able to file their paperwork on time.

From Sunderland’s point of view, if you leave it so late, you run the risk of missing out. The club were attempting to process a number of deals (Josh Hawkes, Benji Kimpioka, Jack Diamond, O’Brien). Some went through, some did not.

The decision to offer O’Brien a move made even more sense when he then dropped out of the matchday squad for the games that followed.

It’s the decision Johnson says is the hardest in the job, over and above picking the starting XI itself. His reasoning was that Sunderland’s late (though excellent) recruitment meant he needed to see his new arrivals in action, having not had the chance to do so through pre-season.

Johnson very publicly left the door open, though, saying he was ‘delighted’ O’Brien had stayed and that he would reassess the situation after a few games.

In the end injury (Lynden Gooch) and a need for freshness accelerated that process, culminating in his recall.

It was one that quickly took extra significance when Broadhead’s superb full league debut was cut short by a hamstring injury. There remains some hope that a scan will give the Everton loanee the all-clear to return to the fold immediately, but Johnson is preparing himself for the possibility of being without him from anywhere up to six weeks.

In that scenario O’Brien’s versatility and reliability again becomes important.

There will, you suspect, be plenty more frustration for O’Brien in the weeks and months ahead. And his contractual status means the situation may well be revisited in January, particularly if Sunderland look to bolster their attacking ranks again.

But for now, that paperwork error could be a boost for Sunderland’s promotion prospects, and hand a popular player a real chance of writing a key part in the story of the season.

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