I realise the value of static and concentric eccentric on the neck, but for us boxers and Muay Thai fighters and the Tank Abbotts of this world a certain degree of proprioceptive or feedback training is needed. This is similar to the training sprinters do on their hammies to train the stretch reflex and reactive strength for the recovery phase of the stride and injury prevention.
Medicine balls (starting lightly) is a great method for this simple principle. I (preferably someone else for obvious reasons)also push on the side of my head and also the point and sides of my chin to facilitate various impacts. One of the fighters I have worked with before I went to uni was very succeptible to body shots. I got him doing conditioning on his body and ribs with a MB with excellent results. Also a partner punching to the body worked extremely well. This is harder due to smaller surface area and has slightly different benifits.
I’m assuming his feedback mechanisms are better conditioned than they were as well as his muscular strength. Can’t wait to get back and try the new hypothesis.