For Australia to defeat India in this Test series, the visitors' spin bowlers must deliver their overs more economically than India's do. That's not merely an assertion but a fact, backed up by the past 20 years of Australian visits to India for Test matches. Controlling the run rate is the key to winning the Border-Gavaskar Trophy.
In the seven most recent encounters, beginning with a one-off match in Delhi in 1996, on only one occasion did the visiting spin bowlers offer superior economy to their home counterparts. It was in 2004, when Adam Gilchrist led Australia in Ricky Ponting's stead and Steve Waugh's "final frontier" was finally conquered.
During that series, Shane Warne served as the tourists' only full-time spin bowler before the fate of the Border-Gavaskar Trophy was decided, with Nathan Hauritz filling in for an injured Warne in the final, dead rubber match in Mumbai. While Hauritz was more expensive and left Michael Clarke's part-timers to strike the most telling blows on a horror Wankhede Stadium pitch, Australia's spin collective ended the series with an economy rate of 3.11 runs per over.
That was enough to edge the likes of Harbhajan Singh, Anil Kumble and Murali Kartik, who were narrowly more expensive, going for 3.12 runs per over across the four Tests. If one 100th of a run doesn't sound like much of a difference, then the other series either side of 2004 offer the context to prove the rule.
In 1996 in Delhi on a difficult surface, India's spinners conceded 2.07 runs per over versus Australia's 3.20; In 1998 it was 2.54 versus 3.43; in 2001, 3.16 versus 3.31. The gap has only grown in more recent encounters, underlining how India's batsmen have set out to destroy bowlers less capable than Warne. In 2008 it was 2.69 to 3.77; in 2010 it was 2.59 to 4.05; then on the most recent trip in 2013 the gap was truly yawning - 2.38 for India's spinners and 4.17 for Australia's.
Clearly, India's batsmen have grown increasingly belligerent in attacking the visiting slow men, while at the same time the home bowlers have strangled Australia's top six with an ever-increasing level of effectiveness. In trying to reverse the trend, Australia have called upon the left-arm spin of Steve O'Keefe, a bowler for whom economy is critical to success.
While it would be easy to conclude that it simply took a bowler of Warne's greatness to achieve the feat of out-strangling India's spinners, closer examination of the 2004 series offers a reminder that he did so by playing very much against type. In fact there were several observers of Warne's approach in the first Test of the series in Bangalore who expressed disappointment at how he appeared to be bowling faster and flatter than in the past, seeking maidens over stumpings.
Yet by the end of the second match in Chennai, where Warne claimed a persevering 6 for 125 from 42.3 overs and became the world's leading wicket-taker in the process, the value of his more conservative, even defensive approach had become clear. At the time, Gilchrist lauded Warne not for his long-standing class, but for his ability to learn how to best play a complementary role in the visiting attack.
"Warney's inevitably going to be compared with his history here, and it's inevitable he's going to be compared with their spin bowlers' results," Gilchrist said after rain ensured a draw. "They are totally different types of bowlers doing totally different roles in their teams. For what Warney's role is in our team, I was thrilled with the way he went.
"He is learning as he goes, which is amazing for the world record holder. He's taking things in from various players, and batsmen ... I've been impressed with that perspective of Warney's game. He's still trying to better himself. I thought it was a terrific effort here. Stats don't lie. He got six wickets for us in a very important innings. If they had got 200 or 250 ahead we were dead and buried. He was a major reason they didn't get there."
Intriguingly, Australia's selectors deliberately ignored another "defensive" spin option for the tour by choosing Mitchell Swepson ahead of Adam Zampa, who was compelled to content himself with a couple of Twenty20 appearances back home instead. The interim selection chairman Trevor Hohns, himself a former wristspinner, stated that "we thought we would go for a more attacking leg-spinner over a defensive spinner".
Hohns, funnily enough, had been the selection chairman at the time of the successful India tour of 2004, alongside the man who would replace him, Andrew Hilditch. Though he was often criticised during his tenure, Hilditch at one time offered his own opinion on "attacking" spin bowlers.
"The word attacking is a bit overrated really, to assert pressure from one end is attacking cricket," he said in early 2009.
"Some spinners you regard as more attacking might spin the ball a bit more, they might be a bit more erratic, but really it's about asserting pressure and performing the role the captain wants."
For now, the need to assert said pressure most likely rests with O'Keefe and also Nathan Lyon, one of the bowlers clattered about four years ago. While Lyon was again expensive in the Mumbai tour match preceding the Pune Test, he has at least exhibited something approaching the attitude that Warne carried into the 2004 series.
"If you are going to come out and try to take a wicket off every ball, you are going to get hit for boundaries," Lyon said this week. "For us, coming over and competing here is about building pressure, either with quickies or spinners at the other end. Try to give minimum runs and make the Indians play the big shots.
"That's where we are going to build pressure. That's how you build pressure and take wickets. If you go out thinking that I have got 10 overs and I am going to get them in 10 overs, you are on a slippery slope to nowhere really."
Nowhere but defeat. All the available evidence says as much.