While doing research for the book, I learned that steroid testing is a very complex science, and there are so many reasons why the test results cannot be treated as "definitive" -- as I show in the book, the errors are not symmetric either: the information value of a "negative" finding is low while a "positive" finding is usually credible.
Then, I came across this Yahoo! article featuring NFL manager Ozzie Newsome defending the league's testing program, repeating a laundry list of nonsense.
No. 1, I think we probably, in professional sports, have the best testing of all the four major sports.
Professional sports in general, and US professional sports in particular, have less stringent testing than amateur sports so comparing them against each other isn't saying much.
Our testing for performance enhancers goes year-round [and] they’re random. So, if there’s anything that any of our players are taking, then they will be found out about because they will test positive for it, and there would be a suspension.
Taking the second sentence first: He asserts that a drug test is 100% accurate, there are no false negatives, and everyone who takes something illegal will test positive. That's the exact opposite of what is happening out there. There are a lot of false negatives; most dopers are not caught.
His first sentence is useful as it explains why it is extremely hard to catch dopers. Year-round testing is standard fare for any serious drug-testing program: this is to expose off-season steroid use. It's a myth that atheletes consume steroids -- and I'm using this term loosely to include other performance enhancing drugs -- right before an important competition or only during the competitive season; instead, it is more effective (not to mention less prone to detection) to use them during off-season training. (Off-season steroid testing is controversial and operationally complex because it requires athletes to disclose their whereabouts at all times so that inspectors can show up unannounced. It also has led to hilarious scenes of athletes evading testers, with ingenious reasons for why they were where they said they would be when the testers showed up.)
Random testing can mean one of two things. If he means unannounced timing, then this also is standard for any drug-testing program. In fact, any testing program in which testers do not show up unannounced is not serious. If the athlete knows he/she is being tested tomorrow, there is no chance that the test will come up positive.
If by random, he means random selection of who to be tested, rather than random timing of the test, that's another matter. I'm not sure that random selection is the desirable option; the alternative would be targeted testing, targeting the people who have more incentive to cheat (ironically, these would be the higher-ranked athletes).
This situation reminds me of the so-called "random" bag search in New York subways. If I'm concerned about safety only (not fairness), a targeted bag search will be much more effective than a random bag search. Imagine that the random search is implemented by stopping every 50th passenger walking into a station. This search policy will yield a high rate of false positives, that is, innocent people being searched. In addition, it will also have high false negatives because you won't stop a suspicious looking passenger if he/she doesn't arrive at the 50th, 100th, 150th, etc. slots. (If you do stop such passengers, then the policy cannot be described as "random".)
That being said, if there is a product that he’s taking, and he’s passing the tests, then I can’t explain that one.
He's not trying hard enough. Just off the top of my head: he's a false negative (which is a highly probable scenario as explained in the book); he's lucky (how many times is each athlete tested each year anyway?); he's taking a new steroid that doesn't have a test yet; he's taking a masking agent that doesn't have a test yet; he's taking a known steroid that the NFL does not currently test for (e.g. HGH); he's taking a known steroid for which a reliable test hasn't been devised yet; he was on an off day of his steroid regimen when his urine was collected; he's got a legal pass to take the steroids (this is called Therapeutic Use Exemption); he's used someone's urine or other tricks; etc.