Australia are not the same team without a 100% fit Mitchell Starc - and that includes when Starc is actually playing.
Conspicuous by his absence in Melbourne, nursing a bruised heel some way back towards full health as the rest of Steven Smith's bowling attack was humbugged by a lifeless pitch, Starc returned for a home SCG Test, with all its attendant fanfare.
If the start was delayed by wet weather, there was nothing damp about Starc's expression, grinning broadly in the minutes before he sent down the first over in front of family, friends and teammates happy to see him back. There was promising swing and bounce in that first over, too.
But Test cricket is not an affair in which a few swift overs are enough. Sustained speed is the thing, demonstrated so ably by the Australians when the Ashes were up for grabs. As the day wore on, it became increasingly apparent that Starc was not exactly near to his best nor his fastest, giving England's batsmen the sort of respite they must have pined for during the decisive first three matches.
It was in terms of speed that the difference was most apparent: where Starc had been part of a bowling attack that averaged 141kph in Brisbane, Adelaide and Perth, here he seldom passed 140kph, and slid as low as 127. The second new ball did swing in Starc's hands, but it was more charity than venom that had Joe Root clipping a half volley to square leg in the day's penultimate over. A subsequent yorker to Jonny Bairstow ticked over at 142.5kph, and Hazlewood's follow-up with the new ball meant Australia broke even on the day, but the earlier dip to 127kph will have been noted.
That, coincidentally, had been the speed of the first ball Jackson Bird delivered in Melbourne, where Alastair Cook in particular took advantage of Starc's missing pace, left-arm variation and penchant for reverse swing. This time around, Starc's presence at considerably less than his best and fastest underlined the difference between "100% fit" as Glenn McGrath had described it pre-Test, and "fit to play" as wounded cricketers over many years have protested to captains, coaches, selectors and medical staff.
Years of careful planning had gone into ensuring that Starc, Josh Hazlewood and Pat Cummins would be in the former category for the Ashes. Helped significantly by the pace-friendly environment in which young fast bowlers are raised, Australia's approach is nonetheless different to many other nations, emphasising strength and conditioning training to enhance speed, maintain it and also ensure a bowler's upper register can be reached within a few balls of starting a spell.
Dips in pace are carefully monitored, and both Doug Bollinger (in 2010-11) and Peter Siddle (in 2014) were dropped for slipping too far below the preferred level. Equally, Chadd Sayers has been left in international selection purgatory for lacking the extra few kilometres so beloved of the selectors, who want impact from their fast bowlers, used adroitly by their captain.
Never was this more evident than in Mitchell Johnson's shattering influence as a short, sharp shock spell bowler in 2013-14, when Michael Clarke harnessed him with rare expertise. That template was more or less followed four years later with Starc and Cummins. Hazlewood, meanwhile, has benefited from targeted training designed to extract greater swiftness from his action, whether through a faster run-up or more efficient direction of bodily force through the crease.
At the same time the number of balls bowled by each fast man is carefully monitored - a contentious element of the management of many pacemen around Australia, but based on the principle that a bowler's highest velocity simply cannot be sustained beyond certain levels of fatigue or repetition.
"It's something we do really well in Australia and I put that down to the coaches and the medical staff," Cummins said this week. "They realise you can only bowl so many balls a year or in a couple of weeks or whatever the period is, and as fast bowlers they want you bowling as fast as you can for that.
"Most of the balls we bowl in the nets are for a purpose, we want to try to get better or get our body moving, we won't just bowl for the sake of it. Sessions like a couple days out from a game we just want to try to blow the cobwebs out and get our body moving so that once we come on [to bowl] it doesn't feel like it's been too long since we've bowled and that first spell feels like we've found that balance between being fresh but also ready to go flat out straight away."
Balance was a consideration for Australia ahead of Starc's selection. Pointedly, Smith spoke on the eve of the match about advising Starc to take care of himself in this match if he was passed fit to play, and not risking the potential to cloud his availability at full speed for South Africa. "I think the break he's had from bowling has helped his heel heal," Smith had said. "It's coming along nicely so he's confident and you've also got to take the player's word sometimes. Hopefully he gets through and he's fine.
"[My advice is] make sure you're completely fit and don't be doing further damage. We've obviously got some one-dayers after this and Twenty20s and an important series in South Africa as well. So that was the conversation I had after the Perth Test match - we've wrapped up the series, which is great and we want to continue winning, that's important, but you're a key member of our line-up and don't do further damage because we need you in South Africa."
At the same time, Starc naturally wanted to play at the SCG, to perform for his home crowd and also to feel he was ending this Ashes series as an active participant rather than a cussed spectator. It was a fair decision to trust Starc, given his 40 Test matches worth of experience and assiduous efforts to get himself fit after the heel problem, including a teetotal night in Perth after the Australians had secured the urn. But his off-peak display on day one provided a reminder that those extra few kilometres really are critical, not only in edging Australia ahead of England, but giving them the best chance of also vanquishing South Africa.