I agree with Steven on this one. There are a few things to consider here, especially when a strength and conditioning coach is working with a team: A) They are mostly working with groups, B) They often have a set time period ( one hour) to work with their athletes. This means that everything the coach does has to be geared towards getting his priorities for a team accomplished in that small time frame.
Now in the book he doesn't really mention the condition of any athletes in particular. I know when working with athletes in my gym, they won't stretch unless you make it a requirement. It has been noted by many sources that if static stretch allows an athlete to get into safer positions while working out, (i.e maintain lumbar curve when squatting), then it is beneficial to have them stretch before working out.
Also I'm sure Boyle was referring to when his athletes are in-season, meaning that the athletes are working more to prevent injury and stretch, so they are not handling loads that are too significant, meaning that there is less chance for injury.