Why do people keep saying this? It just isn't true. In the same survey they used to analyze the need for HawkEye, and they determined that foot fault calls were made correctly virtually all of the time. There wasn't a single case of a false positive foot fault call in the entire study! It is an easy call to make accurately, and that was definitively proven in a scientific study. Sheesh. In fact, human umpires had a smaller margin for error than HawkEye did when dealing with slow-moving objects (a sliding foot was found to move at less than 5mph).
The call is an easy and clear one, and things only get muddy when you try to insert a subjective element into the equation, such as "blatant". It is much easier to determine if a foot fault occurred or not than whether it was a "bad" one. As the sport currently stands, linespeople are not allowed to make ANY judgement calls of any kind. Their job is completely objective. The only officials with any subjective power or interpretive roles are the chair umpires and tournament referee. Putting more random power in the hands of lower level officials only risks damaging the quality of officiating, not improving it.
First off, what study are you referring to? Is there a link you can give me or point me to a book or article somewhere where I could read this study for myself?
Secondly, which is it - "
they determined that foot fault calls were made correctly virtually all the time" (which means the percentage of correct calls are below 100%) or "
There wasn't a single case of a false positive foot fault call in the entire study!" It has to be one or the other - not both.
Finally, as I've said before - electronic line calling isn't new. They've played matches on courts that were "wired" to call all the lines, and it worked. Not flawlessly, which is why it was nixed for implementation at the '93 U.S. Open, but it worked. Back then there was no study, no polls or anything of the sort. Just the desire to increase the accuracy of line calling in the sport.
As for foot faults, yes, they are infinitely easier to call compared to balls that are sometimes moving in excess of 130 mph - no argument there. My contention is, and it's along the lines of what Max Ply stated, if your foot is touching the line by 3 to 4mm, it's a foot fault, but no human I know of is going to dectect it. They could say "it looks like it's touching", but there's no possible way they could be sure. Conversely, if it's 2mm shy of touching the line it's not a foot fault - no question, it just isn't. Is it close? Very, but that doesn't make it a foot fault.
Am I advocating changing the rules because of the "possibility" of some foot faults or non foot faults being called incorrectly. Not at all. My bottom line is it's ludricrous to believe that just because you don't hear it called often doesn't necessarily mean it's not happening or that just because it is called that it's absolutely, 100% a foot fault.
Try positioning yourself on a tennis court in a chair where the linesperson would be that monitors foot faults (at least 20 feet away from the server, have someone place a shoe right up against the line. Direct them to make it either just touch the line or place the shoe just off the line...and I mean barely, then sit in the chair and see if you can tell if it's on the line or off. You'll be able to guess at it, you'll notice that it's obviously very close, but you won't be able to "see" a gap or accurately detect the absence of one.