After just one season on NBC's The Biggest Loser, Anna Kournikova has left the show, making the tennis champion the first in what may be many replacements for Jillian Michaels.

After Michaels left the weight-loss reality competition last year, producers chose Kournikova, along with another trainer, Dolvett Quince, to work with longtime Biggest Loser trainer Bob Harper for Season 12.

Rocky and Unsympathetic

The hire of attractive, camera-friendly Kournikova seemed like a great choice to some: the tennis pro was an amazing athlete with great name recognition, and had always been in excellent shape.

She also spoke of a connection to those whose self-esteem plummeted from weight gain. She said that years in the media spotlight had made her hyper-conscious of her appearance and caused her to struggle with insecurity and feelings of inadequacy.

But she struck others as the wrong choice right from the beginning, and some weren't surprising by her leaving The Biggest Loser after only one season on the show.

Some contestants found Anna Kournikova's style as brash as Jillian Michaels without the underlay of genuine sympathy and commitment that the longtime Biggest Loser trainer has always exhibited.

Kournikova did not often sympathize with her overweight and obese contestants, talking about her tough upbringing when they complained about their training being hard.

Whereas Michaels would first have yelled at them to shut up, and then pried out the real reason they became obese in the first place, Kournikova seemed to pass over any underlying issues for weight gain, something that rubbed contestants, and viewers, the wrong way.

In one memorable instance, Kournikova told good-natured Joe Mitchell that all he had to do to lose weight was essentially to man up and get over any issues in his past.

Her track record of weight gain was also rocky, making the reason her being out more understandable. The theme for Biggest Loser season 12 was Battle of the Ages, and Kournikova was stuck with the senior division. Her team struggled, especially in the beginning, losing both challenges (understandable) and weigh-ins (less so to viewers who've seen major weight loss from older contestants).

She fixed my thinking.

Each week when eliminated contestants were interviewed however, those on Anna Kournikova's team consistently praised her. This praise even came from those, like Mitchell, who initially bristled at her seemingly unsympathetic demeanor-- Mitchell has said the tennis player was the key to his weight loss success, and claims she fixed his thinking about food and weight.

Anna Kournikova's rep meanwhile, reports that Anna was 100 percent not fired from the show. A statement by Kournikova said only that she enjoyed her time on the Biggest Loser ranch, and would miss her contestants after leaving The Biggest Loser.

Although I will not be returning as a full time trainer on season 13, I will always be a part of The Biggest Loser family and my commitment to bettering lives through health and fitness will continue, she said.

The show just wasn't the right fit for her.

The show just wasn't the right fit for her, a source close to Kournikova told People Magazine. Some of her contestants meanwhile, though still praising her commitment, has additional insight as to why Anne Kournikova couldn't fit into Jillian Michaels' shoes.

One of the things about The Biggest Loser is that there's a difference between someone being able to train people versus training overweight people, former contestant Patrick House said. Bob and Jillian are great at training obese people and pushing them to their limits and getting more and more. I think you have to adapt to that and I think that's what she struggled with.

To say the tennis champion would have done better if she'd simply been a second Michaels however, would be a mistake.

I think one thing Anna did was that she never tried to be Jillian, Biggest Loser alum Hannah Curlee said. For her that was her biggest achievement. Because no one else is going to be Jillian, no one is going to replace her.

Though Kournikova emphasized discipline over inspiration--no mistaking this tennis player for a life coach like Bob Harper-- the main issue may simply have been clashes with the staff. A source on the show has called working with Kournikova a nightmare, and numerous reports claim she clashed frequently with the staff of the NBC weight loss show.

Perhaps Anna Kournikova's reason for leaving The Biggest Loser was not so much that she wasn't Jillian Michaels as that she wasn't right for NBC. For the sake of The Biggest Loser show's future, viewers must hope that is the case.