To clear things up, the servers have lately had issues, which cause players to appear to the side. For example, if you go to the parkour lobby, you're sure to see people phasing outside of the walls of the map. In addition to this, "sneaking" and moving to the very edge of a platform causes you to lean off of the very side of the block, as if you're actually not on the block at all. It's a normal element of minecraft, as apposed to your avatar walking very carefully on the block to not fall off, like they would in a realistic game. Don't worry about it, it's normal. (just assuming that you're new)
Finally, you need video evidence of hackers for them to be penalized.