David Miller's evolution from the man with the mischievous mantra about hitting balls out of parks into a mature and measured middle-order batsman could serve as a major boost to South Africa's chances at the World Cup according to Hashim Amla, who added his voice to the chorus of praise over Miller's recent form, headlined by his maiden ODI century three days ago.

"David in good form means we have a No.5 batter who is going to be dangerous at the World Cup," Amla said ahead of South Africa's final ODI against West Indies. The Centurion match is South Africa's last competitive match before the tournament, where Miller is pencilled in for the new position after earning an elevation.

In the two innings in the series in which Miller has made significant contributions, he has been deployed at No.5, with good results. Miller scored 70 to set-up South Africa's win in the first ODI and an unbeaten 130 in the fourth and showed that, given time at the crease, he can act as an anchor as well as an aggressor.

"Everyone was really pleased for Davy because he showed a side of his batting that people hadn't seen before, where he batted for a long time, shepherded guys and almost took a senior role. That's a wonderful thing for us to have," Amla said. "He has played 62 matches, and has a fair amount of experience. To see David take another step up is good for us."

It is especially beneficial to have Miller shoulder responsibility in the middle-order because that has been the area which has let South Africa down in major competitions before. Even before this World Cup has begun, that aspect of their game has been spoken about as the Achilles' heel, primarily because of the personnel South Africa have picked.

Farhaan Behardien "falls into the finisher's" role, Amla confirmed, but with a modest international record - an average of 20.86 from 20 ODIs - and two cheap dismissals in this series, he has yet to earn the full confidence of the critics. At least the team is not shying away from that. "It's unfortunate that he hasn't got the runs that he would have liked to but no-one can argue with credentials in domestic cricket," Amla said. "He has been the best finisher in the game for the last few years for the Titans."

Behardien had an impressive start to the domestic one-day cup, which started late last year and will continue through the World Cup, and was not dismissed in five innings to earn an average of 229. Inflated as that number may be, among his contributions was a century and a fifty and Amla expects that to translate to international level soon. "Hopefully it's a matter of time before his true worth really shows."

And if it doesn't, South Africa have come up with another use for Behardien. "Although he hasn't got many runs, with the ball, he has been uncanny in getting crucial wickets," Amla said. "He is very wily. It's a different type of bowling from South African cricket has had - medium pacers, skillful arts here and there, he has held his own on the bowling front."

Behardien is expected to share the duties of the fifth-bowler with JP Duminy and has so far showed promise. His three scalps included Marlon Samuels and Denesh Ramdin in the fourth ODI and even Darren Sammy hinted that he had become a bit of a golden arm for South Africa. "You saw Behardien bowl and take two key wickets. On any given day, a bowler who is bowling well is the one you have to respect," Sammy said.

Both he and Rilee Rossouw have been identified by Amla as the men who need to make big statements but he stopped short of calling the reserve batsman a soft spot for a team he joked doesn't have any obvious ones. "For them, they want to get more runs under their belt and that's is the purpose of a game like tomorrow," Amla said. "Overall, we've been playing good cricket, we've got some amazing players and the team is in a positive mindset which is wonderful. In terms of weaknesses, I should ask the journalists, they generally pick those out."