In physics, the law of conservation of momentum states that the total momentum of any group of objects remains the same unless outside forces act on the objects.

Watching an average game of AFL, this theory holds pretty true. Take Lions v Kangaroos last week. For the first quarter, momentum was oozing out of the Kangaroos' forward line. Then the tide turned, and the momentum moved to the Lions. With it came confidence. The ball that only five minutes earlier was dropped, now sticks. The ball that ricocheted off hands now hits its target. The ball that hit the goalpost now floats over the goal umpire's head.

The team with momentum always looks like it has too many players on the ground. But this momentum is transient, and its transfer is the ebb and flow of a contest. It is also a tactic - the reason why teams on a roll are risking much to change tack and run down the clock at the end of the game, and why time-outs are used so strategically in basketball.

This momentum within a game is what makes for the sporting spectacle, but what of momentum within a team over a longer period of time? Is this momentum purely transferred amongst teams, or can teams belie physics and lose momentum of their own accord?

The Melbourne Vixens are a case in point. Last season, they ruled the netball roost. They lost only one game all season, and emerged Trans-Tasman Champions. Their dominance was akin to the Bombers of 2000, the Lions of 2001-03, the Geelong of recent years. Their start to this season was similarly emphatic, winning the first five games in impressive style. After their fourth win of the season, Vixen Renae Hallinan suggested "it would be fantastic to go through the season undefeated...we have the belief in this group." Hallinan's belief in her team was not to suggest complacency, she was similarly steadfast that the Vixens were each day working to "take their game to the next level."

Yet the Vixen's Napoleonic empire came tumbling down in a fashion not unlike Napoleon himself. The Vixens have lost their past six matches, and facing the top of the table Sydney Swifts next week, look unlikely to emerge victorious any time soon.

So how can a team so invincible, so dominant, so brilliant, all of a sudden be so mediocre?

Some cite injury. In netball, with only seven players on the court, the absence of a superstar can be disastrous. The Waikato Magic would require far more than a tactical re-structure to make up for the loss of 193cm shooter Irene Van Dyk, as would the Adelaide Thunderbirds if they were to lose Jamaican shooter Carla Boreggo.

It is true that the Vixens have gone through periods without key defender Julie Corletto and pivotal centre Natasha Chokljat, both players exceptionally skilled and regarded as leaders. Yet both players have participated in losing matches, as well as missing winning matches. While Chokljat's calf injury coincided with the Vixens' initial loss of form, her return to the court has failed to arrest it.

Co-captain Sharelle McMahon underwent knee surgery in the off-season, but has been consistently amongst the best performers. Her leadership qualities are innate and continue to blossom even when the chips are down. A lack of leadership cannot be blamed for the slump.

There are other question marks. Caitlin Thwaites, dominant in the goal circle last year, was dropped for unexplained reasons prior to the pivotal round six loss, and has since seemingly lost both her own confidence, and the confidence of the coach.

The Vixens' loss of form is a complex beast, but form slumps often are. Loss of form is a phenomenon which leaves more questions than answers, but reminds us of the ephemeral nature of sporting success. It is a phenomenon that also more often than not presents excuses rather than solutions.

Sometimes poor form is attributed to off-court matters. Sergio Garcia last year blamed a form slump on a nasty split from his girlfriend. Yet off-court troubles are not always reflected on the ground - the salary cap saga didn't stop the Melbourne Storm posting a big win in their very next outing.

Novak Djokovic blamed a 2009 form slump on a new racquet, rather than any soul searching deficiency in his game. Vixens co-captain Bianca Chatfield preferred self-loathing, describing the team's play as "rubbish."

Rosanna Stanimirovic, a leading sports psychologist at the Australian Institute of Sport, attributes the form slumps of some dominant teams to a failure to adequately review their systems at the fundamental level: "I think when they have a surprise loss it is taken as an aberration. The self-talk is that next week it will be fine, that the system is successful, and that it's not worth throwing the baby out with the bathwater. But the problem is that over time, bad habits can manifest and eat away at the fundamentals."

Stanimirovic's suggestion is that teams that have to fight week in week out for their success engage week in week out in in-depth review of their underlying systems and operations. Glitches are caught early because they must be. There is no room for doing things as they've always been done. Patterns are constantly reviewed for improvement. Yet for successful teams, engaging in deep review at the foundations is risky. What if you find something you don't want to find? Stanimirovic believes "it is human nature. Without even knowing, we don't dig, in case we find something broken."

But it is this ability to combat indifferent form that makes the champions of champions. Grant Hackett barely made the final of the 1500m at the 2007 World Championships, but went on to win silver at the Olympics the following year. He attributes his form reversal to big changes to his daily regime. He changed coaches, got married and moved from the Gold Coast to Melbourne. The changes were aimed at targeting the structural deficiencies inhibiting his improvement, and in doing so, allow him to emerge from a "stale rut."

It may be that the Vixens have undergone a foundational review and are yet to emerge from the other side. Coach Julie Hoornweg has been experimenting with young goalers, and recognises that the Vixens are yet to settle into a comfortable ability to play to their strengths. In fairness, it does take time to learn new skills and strategies.

For the Vixens' sake, let's hope the law of conservation of momentum holds true, and the Vixens' momentum is hiding somewhere they can find it. Fast.