Unless you’re fixated on the intricate details of Labour’s internal processes, you’ll be forgiven for assuming that any MP who is critical of Jeremy Corbyn can expect to be booted out of the parliamentary party. There is currently a drip, drip of stories coming out about Labour MPs being “triggered”. Louise Ellman, who quit the party yesterday citing alleged antisemitism, was one such MP widely expected to meet that fate. But the reality is that, far from facilitating a Corbynite takeover, the trigger-ballot battles taking place across the country have allowed the Labour leader’s critics to come out largely unscathed and better organised than ever.

In the summer, ahead of a likely early general election, the party began its trigger-ballot process. It is a system that gives ordinary members a choice: automatically reselect your MP as a candidate, or trigger a full selection process, which could bring in a different challenger. Under new rules, an MP is “triggered” when the request for a full selection is made by either a third of local party branches or a third of affiliate branches, such as trade unions.

The threshold used to be higher, at 50%. When it was lowered to one-third last year, there was significant concern among MPs. While most were confident of securing the support of half of their branches, many reckoned they couldn’t win over more than two-thirds. And those MPs were frustrated: selection races are fiercely fought, and campaigns are time-consuming and expensive. They argue that their efforts could be better directed towards defeating external enemies. Labour’s ruling body and conference delegates had agreed, however, that it should be easier for members to replace their MP with a fresh candidate.

And so the votes started across the country. Diane Abbott, Emily Thornberry, the Labour leader himself and dozens of others flew through their triggers and were unanimously reselected. The fact that pro-Corbyn figures had an easy time of it surprised nobody. Contrary to the impression you may have gained from reading news reports of triggers, what has stunned insiders is the sheer number of Corbyn sceptics who haven’t been triggered.

Tom Watson, Liz Kendall, Neil Coyle, Jess Phillips, Siobhain McDonagh, Alison McGovern, Rachel Reeves, Ruth Smeeth, Gareth Snell, Wes Streeting – these are all names associated with the so-called “moderate” wing of the party, and yet all have been automatically reselected. It helps that some of the most passionately anti-Corbyn MPs walked out voluntarily earlier in the year, of course. But the bottom line is that, last month, Boris Johnson kicked out his internal critics and Jeremy Corbyn didn’t. Although you wouldn’t know it from coverage of triggers, Corbyn-sceptic organisers are largely delighted and Corbynites deeply disappointed.

Those who have been triggered – Diana Johnson, Margaret Hodge, Roger Godsiff, Emma Lewell-Buck, Kate Osamor and Virendra Sharma – are disproportionately female and BAME. This trend is likely to be more obvious once all triggers are completed. But politically they are a mixed bag. The divisions that caused them to be subject to full selections do not run along traditional factional lines: each triggering was a result of constituency party idiosyncrasies, rather than “left”/”right” battles.

Hodge has openly called Corbyn an “antisemite and racist”. It was assumed when she was triggered that this would be the key factor – and yet that was not the case. She and Diana Johnson both saw remarkably low turnout at their meetings, indicating there was no great push to oust them, but rather a failure to organise, or a faulty strategy. The Osamor result can be traced back to long-standing tensions between minority ethnic and religious groups in Enfield, among other factors. Lewell-Buck’s party has been suspended and put into special measures in the recent past, while Sharma’s is currently in special measures. These are specific, non-factional issues. Momentum is not claiming credit for these triggers.

Keep in mind that this handful of MPs have only been triggered, not deselected. We can fully expect that almost all of those who are triggered will go on to win their selection contests. Why? Incumbents will have their local organisational structures kicked into gear, plus they are automatically included on the shortlist. This has actually been a chance for MPs to identify where their support is strongest and weakest, and to re-energise their base. It is odd to think that this time last year, one of Labour’s affiliated trade unions privately predicted that there would be 40 MPs deselected. We now know there will only be around a dozen triggered, and far fewer ultimately voted out.

Why has the Labour left failed to reshape the parliamentary party through triggers? With parliamentary selections paused, there was little clarity about what was to come, and members wondered why they should incur the risk of the party imposing the replacement candidate. Labour First and similar organisations on the Corbyn-sceptic wing of the party persuaded MPs “under threat” to stay in their constituencies over the summer and during conference and work their local parties.

Most importantly, the defeat is attributable to events at Labour conference 2018. That is when Momentum lost their push for open selections, or “mandatory reselections”, which would have effectively “triggered” all Labour MPs before every election. Instead, the party settled on a compromise: the lower threshold. This has kept in place an antagonistic process, offered the media several negative stories a week about Labour infighting, and bolstered the organisational infrastructure and morale of Corbyn-sceptics.

Far from triggers constituting a Corbynite takeover, Momentum is now being described by triumphant survivors of the process as a “paper tiger”. The network has been hugely successful at winning internal elections, and its venture into policy proved effective at Labour conference last month. But it has missed a crucial opportunity to turf out Corbyn’s detractors. Parliamentary selections in 26 defection and retirement seats are the Labour left’s final chance to create a pro-leadership Labour party in the House of Commons – the results of those contests will be key to the success of Corbynism.

• Sienna Rodgers is editor of LabourList