Washington, Ashwin or Axar? This aside, India have most bases covered ahead of World Cup

Five things India learned (or didn't) over the course of their 2-1 series victory against Australia

That's it, then. India have played their last set of ODIs in the lead-up to the World Cup, and only a pair of warm-up games remain before they meet Australia in Chennai on October 8. Here are five things they learned (or didn't) over the course of their 2-1 series victory.

Axar, Ashwin or Washington?

Fourteen of India's original World Cup 15 will definitely be in the final squad, unless injury strikes at the 11th hour. One spot, though, could still be undecided, with Axar Patel's quadriceps strain creating room for a possible swap.
Axar's recovery is proceeding smoothly, by all accounts, and he is expected to be fit by the time the World Cup starts. But there's still a chance that he could miss out, if the performances of R Ashwin and Washington Sundar against Australia have swayed the selectors and the team management into wanting an offspinner in the squad.
On the batting front, Axar is perhaps India's best option at the troublesome No. 8 spot. He brings left-handedness to a mostly right-handed line-up, can attack and defend, and is an excellent player of spin, which makes him capable of floating up the order if required.
His bowling, though, reduces India's scope for variety, given that he's only likely to play if India pick three spinners, and that his style of bowling is similar to Ravindra Jadeja's. Having two Jadejas isn't a bad thing against predominantly right-handed line-ups, but India might want an offspinner against top orders stocked with left-handers.
And since the Test series against Australia earlier this year, Axar has looked a little off-colour with the ball. He's at his best when he induces doubt in the batters' minds by getting the odd ball to turn sharply against his pronounced angle into the right-hander, but that hasn't been happening for him of late - not even on a square turner in Colombo during the Asia Cup game against Sri Lanka.
There's every chance he could sort out his issues by the time the World Cup starts, but in the interim, India have tried two offspinning-allrounders who have shown how useful they can be. Ashwin played the first two ODIs against Australia, and looked hugely impressive once he got into rhythm, picking up 1 for 11 in his last four overs in Mohali, and three wickets in Indore, including those of Marnus Labuschagne with a cracking reverse carrom ball, and David Warner, who batted right-handed to try and counter his threat.
Washington then took Ashwin's place in Rajkot and conceded just 48 in ten overs on a surface where Australia racked up 352. His bowling had little of Ashwin's guile and variety, but he showed the virtue of hammering away at a hard-to-get-after length while minimising width. With Shubman Gill rested, Washington also got the chance to open the batting. He only managed 18 off 30 balls, but he may have been rusty, given was batting in a competitive game for the first time since August 20. It's also unlikely he'll have to open at any point if he's picked for the World Cup.
Washington shares, in theory, some of Axar's strengths - including batting left-handed - but his power game lower down the order remains largely untested at international level.
Who will India's 15th player be, then?
"I just think we'll have to wait for an official confirmation or for a decision on that," head coach Rahul Dravid said after the third ODI against Australia. "The NCA is in touch with the selectors, they're in touch with Ajit [Agarkar, the chief selector]. I wouldn't want to make any comments on that, but if there's any changes, you guys will hear about it officially. As of now there are no changes."

A sixth bowler is a genuine asset

Washington's performance in Rajkot also took some of the heat away from a couple of India bowlers who endured off days. Prasidh Krishna went for 45 in five overs and Kuldeep Yadav for 48 in six, but they weren't forced to bowl their entire quotas because India had six bowlers to play with.
This wasn't the case in the first two ODIs, where India only played five bowlers. This caused them a bit of trouble in Mohali, where Shardul Thakur leaked runs and struggled physically in the heat, but had no option but to bowl his full ten-over quota.
Having that sixth bowling option, then, makes a big difference, but it isn't always easy to fit six bowlers into an XI. The main reason why India only had five bowling options in Mohali and in Indore was that Hardik Pandya was rested for the series. Without his genuine all-round skills at No. 6, India can't play six bowlers without compromising on batting depth.

Depth is non-negotiable

This was clear in Rajkot, where India's chase ended as soon as their sixth wicket fell in the 39th over, with Kuldeep walking in at No. 8. The lack of a proper No. 8 may even have influenced how the top order went about the chase. There were mitigating circumstances - batting became more difficult for both teams when the ball became older and softer - but India's third- and fourth-wicket pairs between them put on 79 in 89 balls, leading to an acute spike in the required rate.
The security of reasonable batting ability at No. 8 may have allowed the middle order to bat with a little more freedom on another day.
This is why there's no room for Yuzvendra Chahal in India's World Cup squad, and why the third spinner's slot is now a straight fight between Axar, Ashwin and Washington. This is also why Thakur, polarising though he may be, plays so many ODIs.

How can India fit in Suryakumar?

Not every match at the World Cup will be like Indore or Mohali, where the team batting first will score more than 350. Pitches at ICC events tend to be flat, however, so reasonably high-scoring games are likely to be the norm.
On such pitches, X-factor players who can score at T20 rates become hugely valuable. Suryakumar Yadav is that player for India, and he showed exactly what he's capable of in the 50-overs format when he innovated his way to an unbeaten 72 off 37 in Indore. Suryakumar came into this series with an ODI record that didn't reflect his ability at all, and was consequently under a certain amount of pressure from the media - though not from the team management.
Half-centuries in the first two ODIs showed exactly why India had given him so much time and space to get into his groove in the format. They may have also caused a dilemma within the management, of whether to play him in the XI even when all the first-choice players are fit and available.
The third ODI may have intensified this dilemma. Most teams would be thrilled to have all three of Virat Kohli, Shreyas Iyer and KL Rahul in their line-ups, but they are similar players in some ways, and in Rajkot they made, respectively, 56 off 61, 48 off 43 and 26 off 30. Suryakumar only scored 8, but by the time he walked in, the required rate had climbed above 9.

Other teams have bigger headaches

For all the microscopic focus on their weaknesses, India have almost every base covered for a World Cup in Indian conditions. Do they wish that at least one of their main fast bowlers could bat a bit? Or that one of their gun top-order batters was left-handed? Yes, and yes, but these are minor issues compared to those most teams are struggling with.
Fitness is the big one. It wasn't too long ago that India were fretting over three key players in Iyer, Rahul and Jasprit Bumrah. All three are fit and firing now. Other than Rishabh Pant, India won't be missing any high-profile players at the World Cup.
Not every team has been as fortunate. Pakistan won't have Naseem Shah. South Africa won't have Anrich Nortje. Sri Lanka will be without Wanindu Hasaranga and Dushmantha Chameera. Australia are likely to be without Travis Head for at least the initial stages. Persistent injuries have ended Tamim Iqbal's shot at this World Cup. Kane Williamson, who is coming back after rupturing his ACL, will come into the tournament with little or no match practice. The list goes on.
India have been - so far - fortunate with injuries. They'll hope their luck holds over the next few weeks.

Karthik Krishnaswamy is an assistant editor at ESPNcricinfo