I think Salazar pushes his runners through injury and that's why they are leaving. Let's take a look:
*Dathan Ritzenhein: switched to Salazar, had a brilliant ~6mo period where he set the AR, placed highly at the WCs, and medaled at WHMC. Soon after, following aggressive changes to his running form and modification of his training shoes, he developed metatarsalgia. At some point he also developed a neuroma in his foot, and after a 7mi session of intervals on an indoor track, he developed Achilles tendonitis. While Ritz reports that Salazar was unaware that the workout was going to be done on an indoor track, an acute injury like that should heal rather quickly. Instead, Ritz was muddled by injury for months and opted for surgery in April. He also had surgery on his foot neuroma. Ritz developed complications from the surgery and had to have a second procedure due to infection. The incisions from the second surgery became non-healing wounds, which required a walking boot and use of a wound vacuum, which is usually used to treat diabetic ulcers. Curiously, Ritz reported that he could "still run" with the non-healed wound. I don't know of any doctor that'd permit that. As of today, still with Salazar.
*Alan Webb-came to Salazar after leaving his previous coach who had led him to the mile AR. Aggressive running form modification led to Achilles problems and Webb eventually opted for surgery. After rehabilitating, Webb was seemingly returning to form when he abruptly left Salazar for Jason Vigilante
*Kara Goucher-Has been Salazar's "star" female runner for several years, but barring a few "close ones" in the marathon, has not lived up to her 2007 WC bronze medal. Recently left Salazar after a femoral neck stress "reaction" (in truth, early stage of a stress fracture) scuttled her 2011 WC training. Any stress fracture above the knee is extremely worrisome, particularly in women. Recently left Salazar along with her husband Adam, who was also training under Salazar.
*Amy Yoder Begley-made a huge jump from an "also-ran" to a national champion-caliber runner soon after joining the Salazar camp. Struggled with recurrent injuries since 2009, culminating in Achilles surgery in 2010. During rehab, she strained her calf and suffered a stress "reaction" (read: fracture) in 3rd metatarsal. Now, she has injured her left Achilles and again opted for surgery. She is now leaving Salazar.
For one, I am extremely troubled by the fact that three of his athletes have needed (or at least decided they needed) Achilles surgery in the last few years. I've known many runners with Achilles problems, but exactly zero of them have opted for surgery (and all eventually recovered). Why do Salazar's athletes have these recurrent troubles? I suspect he pushes them too hard in training, and has an 'aggressive' rehab program set. Salazar is highly secretive about his workouts, but from what I have gathered, his runners often do extremely difficult, high-volume high-speed workouts in spikes on the track. This type of program, coupled with an aggressive mindset when it comes to injury, could spell disaster for an injury-prone athlete, and I'm worried that is what is happening in Portland.
Of course we've seen this before with John Cook, but in that case it ended up being Cook's sometimes-acerbic personality and his inability to tactfully deal with female runners and the issues inherent with coaching them (recall Cook had NEVER coached a woman before Flanagan).
Drugs are another possibility, of course, as many athletes are jumping ship at the same time, while new recruits (Amy, Mo, Dathan, and probably soon Mad Len) show rapid and dramatic improvement, then later plateau or succumb to injury. Salazar is also known to seek out every possible legal advantage (correcting marginally low thyroid hormones, pairing thyroid hormones with asthma medicine, cryosaunas, artificial altitude, underwater treadmills, brain wave machines, etc.) for his athletes, and some at the LRC rumor mill have speculated his athletes are microdosing or are using next-generation doping agents like SARMs (selective androgen receptor modulators). Unlikely given the integrity of the runners under his tutelage, but not impossible.
While I believe it's his inability to let runners recover from injury that is causing many of Salazar's runners to jump ship, I cannot say for sure. One thing is certain, though: Something is rotten in the state of Oregon...