Was Roger Federer right to criticise Hawk-Eye?

Michael Stich, 1991 Wimbledon champion & Radio Five Live commentator

No

There are lots of reasons why I don't think that Hawk-Eye is good for tennis. It might be a nice show for the spectators and for television but over the long term I think it will take a lot out of the game, especially the interaction between the players, the line judges and the chair umpires.

People are always talking about how there aren't enough characters in the game but the more technology gets involved in tennis, the fewer personalities will show through. You lose a lot by stopping players from arguing with line calls and interacting with the chair umpire.

All the players will end up doing is just playing tennis, not showing their emotions - nobody is allowed to throw a racket these days without getting a warning - and Hawk-Eye is just contributing to that.

John McEnroe was a great player, and very successful, but he is who he is partly because of the way he argued with umpires and used his catchphrase "You cannot be serious ". Imagine what would be missing from the history of the game if that had never happened? Maybe he would not have been the player or the figure that he is right now because he would never have had the chance to challenge the chair umpire's decision and show his personality. Mac also used challenging calls to his advantage, to pump himself up, but if Hawk- Eye had been available then he would not have had the chance to do that. Tennis is a game played by people and people have to be involved - be it players, line judges or umpires. Bad calls will always be made and I certainly do believe that not a single match has been decided by a bad line call in the history of tennis.

Even if Rafael Nadal had been given a bad call on match point down to Roger Federer in the Wimbledon final, then that would still not have been the reason he lost. He lost that match because he failed to take the break point chances he had in the fifth set. Tennis is about fi ghting, it's about commitment and sometimes it's about disagreeing with line calls. I had plenty of times when I didn't like decisions but I never walked off the court and said that's why I lost.

I have never played with Hawk-Eye but I have watched it quite a lot and I don't think it is accurate enough. I am not saying the technology is not good or doesn't work, but I don't think it works well enough to be used in tennis. It is not a live picture. They take pictures from diff erent angles and calculate it through a computer so it is all based on mathematics. Hawk-Eye's makers say they have a margin of error of 3mm but a millimetre in tennis is a huge distance, let alone three , and I don't know how much the system takes into account how much topspin or slice a player has put on a ball, which can have a huge eff ect on where it lands.

I have spoken to chair umpires who say that the reason they don't use Hawk-Eye at the French Open is that when they tested the system on clay, the ball marks proved it wrong time and time again. If it had never been invented we would all have just had to live with the fact that every so often an offi cial makes a bad call - and tennis would be better for it. Taking the human element out of our sport can only be a bad thing.

Dr Paul Hawkins, inventor of Hawk-Eye

Yes

What Hawk-Eye has brought to the game has attracted immense support from the overwhelming majority of players, commentators and spectators. Firstly it puts the destiny of the players in their own hands, giving them the call on when to question the judgment of line offi cials and this has led to far fewer code violations and instances of players getting upset in the tournaments where it has been used than in those that still rely solely on the human eye.

There is a huge amount of pressure on offi cials and players and the intensity of a situation when there is a tight line call makes everyone's blood pressure leap, even those of us who are merely watching. Particularly in these pressure situations, human judgment is impaired. Our computers don't have heart rates and make decisions on the evidence without the added stress of the tension of the situation. It also provides a high level of drama for the spectators that wasn't there before - and this is a secondary benefi t of the system.

On the particular call questioned by Rafael Nadal which provoked Roger Federer's outburst, at 30-30 in the third game of the fourth set, Hawk-Eye called the ball in by a margin of 1mm. This verdict was said by commentators to be wrong - they only get to see the replayonce - but if examined more closely (as you can at www.hawkeyeinnovations. co.uk), that criticism was unfair.

Television replays are deceptive because the cameras are at the wrong angle, looking down at the ball, the ball has a lot of motion blur and compresses and skids about 10cm whil e in contact with the ground. The TV cameras do not work at a high enough frame rate (they work at 150 frames per second) to capture the exact point where the ball fi rst hits the ground. On impact, it will compress so that the bottom half is flat. Then it starts to roll and skid and uncompress. The freeze frame television used showed the ball about 4-5cm out, but at th at stage the ball was decompressing and leaving the ground and therefore much further out than the crucial part when it first made contact with the grass.

There are three main criticisms of Hawk-Eye, the first being that it is not accurate enough. We accept that Hawk- Eye is unable to prove conclusively that the ball was in by 1mm, however we can show that this particular call was within the accepted error of the system (average error of 3.6mm when independently tested) and overall the players accept this. There is also some scepticism about the cost of the system but it was sponsored by Rolex and because of the level of their commitment the event is able to off set all the costs.

Finally, there are some complaints that it changes the nature of the game and I understand the calls to defend the traditions of tennis. But if you look back at the history of the game there were no line judges for many years, the players called the line and the umpire intervened only when there was a disagreement between the two players. Hawk- Eye puts the onus back on the player and could therefore be said to be taking tennis back to its roots.

Hawk-Eye has never imposed itself on any sport, we respond to requests from governing bodies to provide a decisionmaking tool to resolve the tightest calls. Hawk-Eye addresses problem areas where the authorities have decided human judgment is no longer enough.