A boxer's goal should be not to get hit... but saying that with experience your body does learn how to deal with punches, it's all to do with your neck muscles/position of your feet etc and how your nervous system adapts your skeleton/head position accordingly.

So yeah, if you've been off for 9 months then reversibility will have happened (use it or lose it) and you're probably not neurologically wired as well to deal with and adapt to a punch.

If anybody hits you in the right place/position then it will affect you.