It’s theoretically a day off for me as I gear up to cover the Australian Open (I’ll be blogging live from Melbourne during Week Two of the season’s first Grand Slam). But the strikingly thoughtful responses and comments to my last post, along with some of the critical, entirely legitimate questions they raise, call for some clarifications and further comments.

First of all, keep in mind that the doper's best friend is the benumbing complexity and unavoidable ambiguity of the anti-doping effort. A few months ago, I linked to this Outsidemagazine story that makes painfully clear how difficult it is for the dope police to keep up with the bent doctors and juicers; in fact, the effort to police the use of performance enhancing drugs is borderline futile.

But what are you going to do? Allow doping? Talk the talk, but look the other way as soon as there’s even a hint of a problem (as I believe the ATP and WTA have done for years)?

Some of you would like me to delve into the science of doping, and/or present more facts and concrete evidence instead of speculating and trafficking in innuendo. Here’s a question for you: When was the last time a newspaper or magazine broke a major doping story? The recent spate of exclusives from the French sports daily, L’Equipe, don’t count—all they did was jump the gun on announcing positive test results for some athletes thanks to a friendly leaker somewhere in the anti-doping establishment.

Many major, resource-rich newspapers and magazines in this country and abroad employ full-time, highly trained investigative reporters—something I am not. Yet even they have broken precious few primary-level doping stories— that is, I don’t know of any that actually discovered that someone was doping, and proved it. What stories we have all seem to be driven by either announced test results or individuals stepping forward to confess—or fire the first salvos of accusation. This tells you how tough it is to catch a doper red-handed, or to make specific, supportable accusations.

In fact—and this is a constant theme of mine—doping is such an ambiguous subject that the real danger lies in falling into a train of thought that runs something like this: We know doping exists. We haven’t caught anyone doping. Therefore, everyone must be doping. That’s the allure of conspiracy theories—the very lack of evidence becomes a form of evidence.

Why have I wandered into this morass, then? The answer has two related parts:

First of all, at this site I am a blogger—an opinion journalist and commentator. I have neither the mandate nor the responsibility to deal strictly and exclusively with facts and/or the thoughts or opinions of others about those facts. At the same time, though, my opinion cannot ignore or fly in the face of what facts exist. The moment that the facts and my opinion are in demonstrable conflict, my opinions is invalidated. Two plus two equals four, we’ve all agreed; if I insist it adds up to five, that’s my problem, not the number four’s.

Secondly, I am supposed to be a kind of interface between tennis fans and the pro game. Someone higher up in the food chain has decided that it’s worth paying me to comment on the pro game for the benefit of the folks who troll TENNIS.com and/or read TENNIS Magazine, which makes it incumbent on me to report what people in the game are thinking and saying. Trust me: Doping is a burning, omnipresent topic on the pro tour these days. I owe it to you to tackle it, and I am proud that as a blogger I can do that in a way that a newspaper reporter cannot.

Now, for some specific issues. I fear the worst about doping because it appears that the floodgates of bad news have been opened by the change in the anti-drug testing protocols. The player organizations (ATP and WTA) are no longer in charge of testing; when they were, all was quiet on the doping front. It's a different landscape now. You can read why and how this came about at this page of the ITF’s anti-doping website.

Is it mere coincidence that we’ve had a sudden explosion of positive tests? Why have the increasingly puzzling scheduling habits of so many players suddenly become front-burner issues? Draw back and look at this in perspective; it seems to me that we’re in the midst of an undeclared, unannounced shake-up.

The ITF anti-doping website will give you access to lots of valuable information on doping, if you’re interested in details on banned substances, penalties, procedures, etc. This just isn’t an area in which it makes much sense for me to play the expert. Read that article I linked to in Outside; it’s a great primer on the nature of the doping problem.

When it comes to the players, nobody, but nobody, is above suspicion; this doesn’t mean that I suspect everyone—or, for that matter, anyone. It just means that I don’t believe anyone is immune to the temptation of dabbling in performance-enhancing drugs. Top pro athletes, like fabulously wealthy venture capitalists, exist in a different world. They are playing for much higher stakes, with much deeper pockets, which opens up possibilities unimaginable to many of us. I’ll never forget Boris Becker, a close friend, telling me about the transfusions of calf blood he took as part of his drive to remain “fresh” for the game (it was not illegal) when he was making a big push for the No. 1 ranking. Boris was very matter-of-fact and blasé about it; he had to do what he had to do. But it struck me as pure science fiction.

So, as far as I’m concerned, everyone from Roger Federer on down to the most desperate journeyman is a potential doper. It just wouldn’t be fair to look at it any other way. In this regard, some readers accused me of “protecting” Andre Agassi while planting suspicions about Rafael Nadal when I analyzed their withdrawals from the Australian Open yesterday.

The fact is that up-and-coming champs and aging ones are vastly different, and driven by vastly different priorities. I’m not going to rehash the details, but I’ll say that in ways related strictly to his career and family life, it makes a lot of sense, in lots of different ways, for Agassi to skip the Australian Open and start his year a full two months after his younger rivals.

By contrast, the upcoming Grand Slam event offers Nadal his best shot at winning a major on a surface other than clay, and moving one step closer to challenging Federer’s ascendancy—something Agassi is unlikely to do in the foreseeable future.

Given the amount of time he’s had off and the fact that Nadal’s own doctor said in an official ATP press release that his foot is healed, I find his withdrawal from an event that will be without the defending champ, Safin, or Agassi, baffling.

Whether or not there's anything more to this story, I can't say. But I'm going to make a point in Australia to pin down some folks on some of the more compelling issues—like whether or not it's possible to duck out-of-competition testing by simply not answering the door when the testers come around.