Through a variety of factors, ranging from injury to Covid close contact, Australia have been forced to explore the depth of their fast bowling this season, and the results have been very impressive. Now, however, looms perhaps an even trickier decision: whether they can find room to give legspinner Mitchell Swepson a Test debut at the start of a year where he will likely be a key part of their overseas plans on the subcontinent.
It is something of an annual tradition to debate the merits of two spinners at the SCG. The last time Australia played a twin attack at the ground was against Pakistan in 2016-17 when Steve O'Keefe joined forces with Nathan Lyon. They had done the same the season before, against West Indies in a rain-ruined encounter.
Swepson has been in discussions the last two summers - against New Zealand, where Lyon bagged a 10-wicket match haul, and India when Australia could not secure a win on the final day - before the decision has been taken to stick to the more traditional Australian approach of recent times on home soil with three specialist quicks. The latest weather forecast, which suggests showers throughout the fourth Test, does not help Swepson's prospects.
But one key difference now is the development of Cameron Green's bowling towards something that would qualify him as a viable third quick in an attack with two spinners. On the previous two occasions when a pair of spinners were unfurled at home, Hilton Cartwright and Mitchell Marsh were the third seamers - Green's bowling is at a significantly higher level. However, as evidenced by the final day in Adelaide when they were hoping not to bowl him, there remains some caution over his workload, although even as one of three fast men he probably wouldn't need to bowl 20 overs in a day with Lyon and Swepson together.
It's not quite as simple as saying the selectors will give Swepson a game because the Ashes are wrapped up - there are World Test Championship points available, a key stated aim of the Australia side - although it's tempting to say it may not matter what attack Australia put out against this England batting order. But they also need to weigh up the potential benefits of a debut before the tours of Pakistan and Sri Lanka in 2022, followed by India which is now set to be played in early 2023 with the latter two, especially, likely to demand twin spinners at least in some situations.
"If conditions suit, we'd love to give Swepo a crack," national selector George Bailey said. "One of things that's been really hard, and I think Michael Neser has been the biggest example of this, is that being on the periphery of some of the teams, given some of the squad sizes, it can make it really hard because you are so close but you aren't playing as much for your state or even BBL [club].
"We've got no doubt that whether it's the SCG or some time in the future that Swepo is ready. We love everything he's bringing, his cricket is getting better and better, he's a great young leader, we'd love nothing more for him to get an opportunity but it will probably be conditions dependent."
Due to the T20 World Cup where he was part of the squad without getting a game, and the quarantine period that followed, Swepson has played one first-class game this summer - for Australia A against England Lions where he claimed four wickets - meaning he has not been able to build on last season's stellar return of 32 wickets at 23.40 in just five games which played a central role in Queensland's Sheffield Shield title. He became a key second-innings matchwinner, marrying wicket-taking threat with an improved economy.
His first-class record at the SCG is less flattering, albeit from just two matches, with four wickets at 67.50. Last season he was punished by India during the Australia A warm-up match. However, it is worth noting that Lyon averages 40.94 in Tests at the SCG, and that includes the 10-wicket match haul against New Zealand two seasons ago.
"Once you play one, your next one will be a bit better, and you'll be more assured of yourself," Pat Cummins said after the MCG Test. "If Swepson debuted and then suddenly he was off to a subcontinent tour, you'd think that experience is probably a good thing."
The last legspinner to debut for Australia was Steven Smith in 2010. Swepson's career certainly won't follow his path, but at some point in 2022 he will play Test cricket. If that comes next week it would add an intriguing element to an Ashes where every player Australia have used has made an impression.