Shoaib Bashir has become one of the more intriguing subplots of England's car crash of an Ashes tour: present, discussed, but so far untouched. The off-spinner is an untested theory, an idea, or even a hunch. A high release point, yet to actually release a meaningful Ashes delivery.

The 22-year-old has again been left out of England's side for the fourth Test in Melbourne starting on 26 December. "They have got themselves into this no-win situation where Bashir's now become sort of unselectable and that's not a good thing," former England spinner Phil Tufnell told the Test Match Special podcast. "If you are ever going to pick a spinner and he is your specialist spinner then he surely had to play at Adelaide [in the third Test] and they didn't play him. You have got to pick him, otherwise why is he here?"

"If I was Shoaib Bashir, I would have been absolutely fuming." Bashir has played some cricket on the tour, having returned to action following a broken finger on his left hand during the English summer. He featured in a much-derided intra-squad affair at Lilac Hill in Perth before the series started, bowling for both England and the Lions side. He finished with a largely underwhelming 2-151. That was followed by another outing for the Lions against Australia A at Allan Border Field in Brisbane where he ended with figures of 0-115.

Unflattering returns but Bashir's stoicism has ensured he's not been overly affected by the noise surrounding his non-selection. His body language around the England camp is said to have remained positive. One of the reasons he's so liked by England's management is his calm persona. Even though he has been whacked by batters in the nets during this tour he looks to have philosophically taken it in his stride.

England captain Ben Stokes previously said that Bashir is his side's number one spinner, and that a preference for Will Jacks' part-time spin has been "tactical". Bowling coach Jeetan Patel was drinking the Kool-Aid when it was put to him Bashir had become unselectable during the third Test in Adelaide. "Absolutely not," Patel said. "Bash is bowling fine. He's where he's supposed to be in terms of this series."

Bashir, a muslim of Pakistan heritage, was nowhere near those who spent time getting looser in Noosa. When strength and conditioning coach Pete Sim invited the entire squad for a jog along the coast at 07:45, Bashir was one of the three players to set his alarm and actually turn up. A duty of care to Bashir, who does not even have a county contract, has been offered as one reason for his absence. He has another year on his central contract with the England and Wales Cricket Board (ECB). Crucially, and unlike many of his team-mates, he does not have franchise commitments to fall back upon.

He is a young player navigating professional cricket, trying to make his mark in a format where practically every delivery feels like a verdict on his career. Bashir had been considering studying accounting and finance at university when he was let go by Surrey as a teenager so will understand the short-term risk versus long-term gain at play here.

Former England seamer Steven Finn, who went through the 2013-14 Ashes tour without playing a match after struggling with his bowling action and confidence, said there is a "human element" to the Bashir situation. "If you throw someone into this environment and they are not quite ready we have seen how harsh it can be," he said.

England plucked Bashir from relative obscurity. Stokes first saw him bowl for Somerset in a clip on social media, then shared it in his WhatsApp group with ECB managing director Rob Key and head coach Brendon McCullum. Not long after, Bashir was in the England squad with just a handful of first-class appearances to his name.

In 19 Test matches, Bashir has taken 68 wickets at an average of 39. He has an economy rate of 3.78 and a strike-rate of 61.7. His release point of 2.35m is third-highest recorded by a spinner, meaning he is likely to gain more of a slow bowler's key weapon: bounce.

There is more to spin bowling than that, though, which also might partially explain why Bashir has not featured during the Ashes. According to CricViz, Bashir does not get as much drift and turn compared to off-spinners in Australia in the past five years, or indeed bowlers of this type in general across the world. His natural length might also be an issue.

"Across his Test career Bashir's natural length is about 4.67m, and he's most successful with deliveries in the 4-5m length range where he averages 25.9 at a 48 strike-rate," said CricViz analyst Srinivas Vijaykumar. "Off-spinners in Australia in the past five years average 31 in the 4-5m length range and are more effective in the 5-6m length zone. When Bashir's gone a little shorter in the 5-6m range his average jumps to 45.4.

"While globally in the same timeline, off-spinners' success mirrors Bashir's overall numbers but the disparity to the effectiveness in the 5-6m length range isn't as big as Bashir's."

The bowling average for spin at the Adelaide Oval (30.1) is lower than any other venues used in this series with Sydney (50.8) - Bashir's last chance to feature - still to come. It certainly feels one of many missteps by England to play Jacks and not a specialist spinner at Adelaide, although for some it is a case of personnel.

Former England captain Michael Vaughan said Bashir is "not the finished product" and has "never bowled well outside the England team". With the benefit of hindsight Vaughan questioned the whole project. "England have Jack Leach back home. If Leach had played the same amount of Test matches in the past two years as Shoaib Bashir, he would have arrived here with 220 Test match wickets as a hardened senior pro," Vaughan said. "Maybe that's where they got it wrong. Leach is a better bowler now than when he played for England."

Former Australia coach Darren Lehmann said England should have "had a better back-up plan" if they think "have made the wrong call" with Bashir but he deserves a game with the Ashes lost. "I've watched Bashir bowl in the past two days and I see an attacking spinner who can actually get wickets," he said on Saturday's Daily Ashes Debrief. "Sometimes you've just got to bite the bullet and play the guy if you think he's the best."

England have opted not to do that at the MCG for the fourth Test. Whether we will see Bashir in Sydney is anyone's guess.