If you can't move around properly, either due to bad landscape/positioning or you're just bad at running around, then yes. Get below them and out of their reach. Jumping can reduce your mobility, but if you're really good at sprinting right after you get hit (Like using BSM, but you actually double-tap W, so it's legit), then it isn't too much of a problem. But of course, that takes skill to pull off properly, and newer players can't always do it. Jumping is great for moving faster, though. When strafing, I tend to jump around quite a bit (I think).
Often, strafing can deal with block-hitters quite easily. However, if they are good at turning quickly and accurately, you can be in trouble.
Say you're a good strafer, fighting a block-hitter that can turn around well - You can be in trouble. The point of strafing is so that you can confuse and get behind the opponent, but if they don't get confused and keep you within your sights, then what's the point of strafing?
But if you're a good strafer, fighting a block-hitter that can't turn well, then you'd be able to confuse and get behind them.
And if you are block-hitting, then make sure to keep the other person within your sights, otherwise you'll be in trouble.
As for clicking fast... Also, you must make sure not to only block. You have to make sure to click both buttons, rather than just the right click button. Some people say to click both buttons at exactly the same time, but whenever I block-hit, I have to click the left then right button. Dunno why, perhaps it just how my mouse works (It's really old - 2005)
Of course, not everyone PVPs like I do. It would make MCSG a loooot harder if people used all my tactics as well as I do
This is just my take on stuff. If you see that I wrote something that's incorrect, or that doesn't work, feel free to let me know so I can fix it (I really don't want to be misleading other players, even by accident) or if you see that I wrote something the wrong way, either by putting words/sentences in the wrong order, pleeeeease let me know. I'm typing this up really fast, and I'm actually kinda dizzy while typing. So I'm not sure if I'm saying this right.