The tourists' dismal Test campaign ended on a disturbing note on day five of the third Test, when they were bowled out for 160 in 44.1 overs, chasing 324 for what would have been a consolation win.

At one stage they lost 5-23 off 39 balls as their frailties against spin bowling were again exposed. Champion Sri Lankan spinner Rangana Herath claimed 7-64, for match figures of 13-145. He finished with 28 wickets overall at a stunning average of 12.75 and was named man of the match and series.

Australia had landed in Sri Lanka in a robust frame of mind, but they were soon out of answers on how to handle the spinning and sliding deliveries, while lacking enough variety and venom when they had the ball.

Paceman Mitchell Starc was a standout with 24 wickets, while the under-siege Nathan Lyon claimed 16 wickets – the third most of any bowler in the series – but at an average of 31.93.

Smith said he was out of answers when it came to the tourists' woes on the sub-continent. They have now endured series whitewashes in their past three campaigns in the region, losing 2-0 to Pakistan in the United Arab Emirates and 4-0 on their last tour of India.

"It's a hard one to grasp really," Smith said. "It's been a very tough series again – that is our third-straight whitewash loss in the sub-continent.

"What we are doing isn't working; batters aren't adapting to the conditions, spin bowlers aren't adapting to the conditions. I can't fault our quicks, I thought they did a great job, particularly Mitchell Starc, but our batters and spinners are the ones who have to step up and we haven't been able to do that.

"We have been outplayed in every facet of the game. Our plans haven't worked as individuals or as a collective group, we haven't been able to put Sri Lanka under as much pressure as we would have liked."

Left-arm finger spinner Steve O'Keefe was to have been Lyon's partner through this campaign and his absence hurt when he had to return home because of a hamstring injury.

This meant Jon Holland, in place of another injured spinner, Ashton Agar, vaulted into the Test side, but he would have only five wickets at 54.80 in two Tests. The selectors have much to think about ahead of the tour of India in February.

Smith said the tourists had been guilty of letting several encouraging positions slip during the campaign, going back to when they dismissed Sri Lanka for 117 in the first innings in Kandy, but failed to capitalise with the bat.

Smith, having made a century in Colombo, led the tourists with 247 runs at 41.16, while David Warner (163 at 27.16) and an under-pressure Adam Voges (118 at 19.66) were disappointing.

The decision to draft in all-rounder Moises Henriques for the dead rubber was questionable. He made a combined eight runs and was not given a bowl in Sri Lanka's first innings of 141 overs.

Smith said it had been the selectors' call to include him, of which he is not one, and said Mitch Marsh had been the frontline all-rounder, meaning Henriques had not been needed to bowl.

"He [Henriques] was picked pretty much as a batsman," Smith said. "He can obviously bowl a little bit. Mitch Marsh is the all-rounder in the team.

"In these conditions it is the spinners' job to get the majority of the wickets, as the Sri Lankan spinners did – we just haven't been able to do that.

"With the spin bowling, it's about landing the ball in the right area enough, trying to build enough pressure, not let the batters get away. You look at the way their bowlers bowled, they come under the ball, they change their pace really well and they put the ball in the right areas."

Smith praised the efforts of 73-Test veteran Herath, who, at 38, remains one of the sport's premier spinners.

"He's a very tough character to face," Smith said. "He's always at you, he's always at your stumps, he changes his pace beautifully and bowls from different parts of the crease, changes his angles up.

"You never really get a freebie off him or an easy boundary. You always have to work for your runs, which is important as a left-arm finger spinner to the right-handed batsmen, in particular. He is a terrific bowler in these conditions and he has had a magnificent series."