Back in 2006 the Scottish National Party suddenly changed tack. Having long campaigned negatively, it began to exude sunny optimism.

This, I recall the late Labour politician David Cairns telling me, completely wrong-footed Scottish Labour, which had grown accustomed to accusing the Nationalists of “talking Scotland down”.

As the former SNP adviser John Fellows recalled in a recent article, in the wake of the 2005 general election the party “went from employing a sniping, angry tone across our communications and media work to become the positive, aspirational force in Scottish politics”.

Its message was boiled down to two key messages, that the 2007 Holyrood election would be a straight fight between the SNP and Labour, and therefore between Jack McConnell and Alex Salmond as the next First Minister. Every piece of communication in 2006-07 drove home these points.

And it worked. As McConnell later reflected, the SNP “picked up on the fact that Scots wanted to hear positive stuff so they ran with a very positive campaign campaign and we [Scottish Labour] ended up on the other side of that, sounding negative”.

But more than a decade on, it seems to me that what Fellows correctly identified as a “sniping, angry tone” once again permeates SNP communications. Of course, it never completely went away – the “Yes” campaign of 2012-14 was a balance between positivity and negativity – but since the recent election it’s returned with a vengeance.

Even at the height of his powers, Alex Salmond used to employ startlingly violent imagery in talking about Westminster which, as he was fond of saying, would “hang by a Scottish rope”. During May’s campaign, Nicola Sturgeon was similarly bleak, repeatedly warning voters that a re-elected UK Conservative Government would be able to do “whatever it wanted” to Scotland without lots of SNP MPs.

In the last few weeks, meanwhile, the First Minster has branded the appointment of Ian Duncan to the House of Lords and Scotland Office an “abomination” and accused David Mundell and his party of having decided to “shaft and sell out Scotland”. If ever there arose a genuine – rather than a manufactured – grievance, one suspects Sturgeon would find herself at a loss for superlatives.

It’s easier, of course, to be relentlessly upbeat in opposition, much harder to keep it up after more than a decade in devolved government. Indeed, the necessity of defending a deteriorating domestic record means that avoiding an angry, sniping tone is extremely difficult.

Sturgeon, meanwhile, has even begun taking pops at the media, a significant departure for a politician who, since becoming First Minister almost three years ago, has made a point of avoiding her predecessor’s (continuing) histrionic attacks on what he now calls the “deadwood press”.

But since the election it’s unmistakably crept into the First Minister’s tweets. First, she referred to on-the-record briefing from colleagues about her referendum strategy as “media speculation”, then suggested that newspaper headlines concerning a Nuffield Trust report on NHS Scotland lacked “balance”. The financial crisis facing Scotland’s health service, it seems, wasn’t really newsworthy.

I’ve also heard it suggested that Sturgeon is reverting to an earlier political personality, before her election as deputy SNP leader in 2004, when she was widely seen as unsympathetic and aggressive. Although this was never entirely fair, perceptions matter in politics. Think back to the 2015 general election when the First Minister was positive and pitch perfect, and compare that with the Sturgeon of 2017, whose most memorable campaigning moment was betraying the contents of a private conversation to score a cheap – and ultimately ineffective – political point.

This defensiveness extends well beyond the First Minister. Twice last week I had the honour of attracting a ministerial response to my social media output. When, for example, I suggested Highland Spring had received the Salmond treatment in response to (justifiable) concerns from its chief executive about incessant independence chatter, Economy Secretary Keith Brown told me that on hearing their concerns, he’d asked officials to “discuss them further”.

On the surface, this was fair enough, although it didn’t really explain why Highland Spring had felt compelled to issue not one but two contrived statements arguing that black was actually white. The other bit of ministerial feedback, however, was just weird. Moments after I’d tweeted a Guardian story about Canadian Prime Minister Justin Trudeau not meeting Nicola Sturgeon on his recent Edinburgh visit, Shirley-Anne Somerville fired back: “He didn’t meet Theresa May either. Snub to her too or does that just not fit the narrative your going for?”

Setting aside the grammatical error (from the Minister for Higher and Further Education, no less) and the fact Mrs May wasn’t in Edinburgh, what precisely was the point of having a pop at a journalist and the perceived “narrative” of an automatically generated Tweet? It simply came across as needlessly defensive.

Scottish Tory leader Ruth Davidson recently alluded to this in defending her appointment as an honorary colonel (about which, it should be said, there are legitimate points of criticism). Support them or not, she said, the SNP had always been “a serious party of government”, but over the past few months this had been undermined by a “crouching defensiveness over the sort of stuff they would have simply brushed off a couple of years ago”.

The effort, added Davidson, involved in “being so furious all the time must be exhausting”. Not only that, but it leaves the SNP vulnerable to the sort of pivot Scottish Labour fell victim to more than a decade ago. And given that Jeremy Corbyn is now in possession of political optimism, if the First Minister and her colleagues allow themselves to be defined as the narky party, then it’ll make winning the 2021 Holyrood contest that bit harder.

Sure, everyone is tired following a relentless year of referendums and elections, but this goes beyond political fatigue, almost a hint of desperation: The First Minister’s push for a second referendum has fallen embarrassingly flat, as has every tired old attack line from the last few decades.

Over the next four years, therefore, I suspect the cries of “talking Scotland down” (from the SNP rather than Labour) will grow louder and shriller, while the media will find itself under further Twitter fire. After all, what else is there?