I've experience more than a few 'warm ups' that left me colder and stiffer than when I got on the mat. Particulalry in cold weather.
I'd come into the dojo reasonably warm from biking a couple of kilometres to get there, and by the time the 'warm-up' was over I'd be stiff and cold and losing feeling in my feet from kneeling so much and maybe even starting to shiver if the weather was cold enough. Not a great way to then start a class.
Interesting that you mention this.
I recently went to a seminar with a 7th dan, and her warm up was wretchedly inefficient and ineffective. So much so, that I and a few others did our own warm ups on the second day, instead of participating in the group warm up.
I put a great deal of effort and attention into my training, and have long been interested in physiology and movement. I do great warm ups!
I have come to realize that group warm ups suck! They are often necessary for beginners and those who are out of touch with their bodies, but in truth, a warm up is and should be highly personal.
All this talk of "conventional" and "unconventional" muscles is as stupid as it gets. The human body was designed to function in a way the pre-dated the concepts we may have about its functions.
I use static stretching. I even use it sometimes in my warm up. But more often than not I am using a combination of some sort of circling or dynamic mobility or active stretching (using muscle contraction to stretch antagonistic muscles) or self-myofascial release (foam rolling).
Besides the negative impact on performance, static or passive stretching actually make your joints more prone to injury.
The bottom line is that the human body responds much better to taking it through a range of motion under its own muscular control than it does to stretching beyond those limits.
It is not difficult to put together a wonderful warm up that takes only a few minutes... This isn't rocket science!