By Martyn Herman

ISTANBUL (Reuters) - Statistically Caroline Wozniacki remains the best female tennis player in the world but the controversy over her number one status showed no signs of abating after her season ended in disappointment at the WTA Championships.

However, when asked who was the stand-out player of 2011, none of the seven other women who qualified for the season-ending finale in Istanbul named Wozniacki.

Former world number one Maria Sharapova, who battled back to the top four from injury, was mentioned, as was the player of the moment Petra Kvitova, who capped a remarkable season by winning the Championships undefeated on Sunday.

But what of Wozniacki?

While the WTA Tour points to the fact that the rankings system rewards consistency, the fact that Wozniacki has so far failed to shine on the biggest stages gives plenty of ammunition to those who say she is there by default.

Wozniacki, the theory goes, has benefited from injuries to the likes of Serena Williams and Kim Clijsters and from the fact that some of her peers are still developing their games.

Williams, and before her the likes of Martina Navratilova, Steffi Graf and Monica Seles, used to provide the ultimate benchmark for women's tennis in various spells of domination but Wozniacki, despite racking up victories, points and dollars, lacks that authority.

All of those, with the exception of Hingis whose brain was possibly her greatest strength, could also dominate opponents in a way that Wozniacki's solid percentage game cannot.

When it gets down to the later stages of a major, the chances are Woznaicki will run into a player with the weapons to break down her barricades.

"She's certainly not the best player in the world at her best, but at her worst she's probably the best player in the world compared to the others," former men's world number one Mats Wilander said this week.

MAJOR STRENGTH

It is a recipe for the kind of consistency in results which U.S. Open champion Samantha Stosur believes is Wozniacki's major strength.

"Kvitova's got a lot more visible weapons than what Caroline has," the Australian told Reuters after losing to Kvitova in the semi-finals at the Championships.

"But what Caroline does very are the things that a normal tennis fan may not necessarily see. I mean, she moves well, competes extremely hard, and really makes you work for it."

Stosur also said the way the rankings points are structured favoured Wozniacki's habit of rarely losing early in a tournament.

"I think you do get rewarded for winning a grand slam and you definitely get the most points by far if you're able to do that," she said. "But we've got nine other really big tournaments, and four of those are not too far behind a slam.

"They're the tournaments that Caroline manages to do very well in, week in and week out. That's how she gets her points without winning a slam."

After a rest starts the work on taking the next step in her career, according to her father and coach Piotr -- a firm believer that his daughter should get more plaudits for finishing first in the rankings for a second year in succession.

"I know she has not won a grand slam but she has had many good results so it's a fantastic achievement," he told Reuters.

"There are many, many players now, probably the top 30 who play to a very high level. Before maybe it would be hard from the quarter-finals now the first three rounds are very tough.

"A grand slam is the next step for her but and it's a big ambition but we are taking it step by step."

With players such as Kvitova and Azarenka breathing down her neck and Serena and Clijsters soon to return to action, however, the worry for Wozniacki is that step may be backwards.

(editing by Nick Mulvenney)