Glad you're okay after your experience.
Yes, 'real world' experience can often reveal a potential 'disconnect' between training and being able to apply it, as well as whether the training is even applicable and sufficient to meet the needs of actual situations and circumstances encountered.
Unfortunately, not everyone has the inclination or opportunity to acquire experience so they can continually evaluate their performance under the stress of unexpected, dynamic, rapidly evolving, chaotic physical encounters where mental & emotional preparation is arguably of even greater importance than physical and equipment preparations considerations.
Who in their right mind wants to experience those situations if they can possibly be avoided, though, in the first place?
Sometimes a job or service responsibility places us in situations and circumstances where things like that can occur, though, which is why LE & military responsibilities come with at least some level of required training ... training which has hopefully been based in the lessons learned by other folks (and probably at dear cost).
Training can be effectively used in situations for which the training has been designed to be appropriate and effectively employed. That's the trick, though, isn't it? Having training suitable to the desired circumstances ... and then being able to retain and maintain a high level of those skills, coupled with the mental/emotional state of mind necessary to effectively perform them.
Luck and good timing shouldn't be snubbed if it comes our way, though, either.
I can understand your feeling about the rush and shakes after the event. After having been involved in the diligent and serious practice of some martial arts for almost a decade, the first time someone tried to kill me with a knife it resulted in the shakes and nervousness ... afterward. During the situation I resorted to my training and was able to prevent suffering serious injury. I was fortunate that much of my training had been rooted in practical methods and techniques. It probably helped that my first instructor had survived a lot of special activities in SE Asia in the late 60's, I suppose, and that another older instructor had a very 'reality-based' training philosophy with some aggressive training opportunities.
By the time I entered LE work I found I had a significant inculcation related to mental preparedness & state-of-mind. My LE experiences built upon that foundation.
In a perfect world I would prefer my children and grand children were not required to learn those lessons, though.
The mind must be prepared.
Physical preparation is important.
The focus on equipment shouldn't distract, or detract, from mental/emotional/psychological preparation which may be critical to surviving a situation and then being able to continue to enjoy the good quality of life previously experienced.
If you don't mind my asking, however, how did you manage to find yourself in the situation where you were tackled from behind? Job related?
Awareness and a realistic perception of your immediate environment (without being paranoid) can help reduce the risk of exposure to some types of situations. I'm guessing you already reassessed what happened, and anything you could have done to reduce the potential for this to have occurred in the first place. Care to share any of those thoughts?