Thursday, April 17, 2008

So Tennis Vision isn’t always 20-20

More than any other player, Serena Williams can probably be credited with influencing the decision to include technology as an integral component of professional tennis. One match in particular, against Jennifer Capriati at the US Open in 2004, resulted in insistent calls to use technology to help adjudicate in situations in which line calls are ambiguous.

I tried finding this match on youtube, but wherever I looked, I ran into one of two error messages: “This video has been removed due to terms of use violation” or “We’re sorry, this video is no longer available”. I guess someone somewhere has decided that this important piece of tennis history needed to be squelched forever. Well forgive me for bringing it back up.

This match is important because it became part of a significant movement that has forever changed the way tennis is adjudicated professionally. And despite new research suggesting that the new technology may not be all it is cracked up to be, I’m sorry but there is no going back. Hawk-Eye is here to stay.

But before we go forward we need to go back, to that infamous match that Serena played against Jennifer Capriati, who was then enjoying a second wind in her career. Capriati lost the first set 2-6, but came back to play some scintillating tennis that won her the second set 6-4. In the first game of the third set, the chair umpire called a ball out that the line judge had called in. The ball had fallen on the far sideline of the umpire, so she was actually not in the best position to overrule the call. But overrule she did – and handed the game to Capriati. That was the first of four horrendous line calls that would end up costing Serena the match. ESPN’s computerized Shot Spot confirmed that all four calls were incorrect. Fans were stunned. The media documented the sense of outrage. The Association of Professional Tennis later apologized to Serena. The umpire was banned from adjudicating any more main draw matches at that tournament. Tennis fans joined the call to use the existing technology to prevent such unfair outcomes in the future. And many of the more influential tennis pundits supported this call.

Hawk-Eye was officially incorporated into tennis adjudication in 2006, but came fully into its own in 2007. Players are allowed two challenges per set, and an additional challenge if the match goes to a tiebreak. If they are correct, they keep the challenge. If they are wrong, they lose it. Most of the center courts at the top tournaments are now equipped with instant replay screens, which the chair can consult to confirm the accuracy of line calls. Fans love the new technology. Challenges add a dimension of excitement to a match that may not otherwise exist. You would think therefore that everyone would be happy.

Not so fast. Comes a report out of the University of Sussex, looking at Hawk-Eye data gleaned from 1,473 challenges made by 246 singles players or doubles players from 15 tournaments in 2006 and 2007.

Turns out that 39.3 per cent of the challenges were successful, which confirms that line judges do sometimes make wrong calls. But despite this, line judges turn out to be more accurate in their judgments than players themselves who are much more prone to error. And more errors seem to occur on the base and service lines than on the side or centre lines where the ball may move more slowly past the line judge and may therefore be better visible to the naked eye.

But some tennis professionals remain unconvinced that Hawk-Eye has been all good for tennis. Some were convinced that it might lead to gamesmanship, similar to the way sick time-outs and bathroom breaks are sometimes exploited by losing players during a match. However, the new research suggests that most players use their challenges in good faith. I believe this to be true for the simple reason that players only have two challenges, which does not lend itself to gamesmanship. However the proposal to increase the number of challenges to five certainly increases the likelihood of exploitation.

Roger Federer has spoken out openly against Hawk-Eye and similar technologies. He believes that they have taken some pressure off the umpires but have added more to the players, which “makes it really hard for us. They [the umpires] tend to now just let us do the work, the tough stuff. They let us get embarrassed, basically”. He’s got a point. There is always a loud groan when a player challenges and loses. It can be a bit embarrassing.

Others believe that the accuracy of the technology may be overrated. Tennis commentator, Mary Carillo, has compared Shot Spot to presidential polls – we need to keep in mind that “there’s about a 3 percentage point margin of error”. Which makes the system imperfect and therefore fallible. But clearly not as fallible as the human eye.

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