Well, I am all new to pixel art, I started about 6 months ago. I have always loved pixel art and gave it a try. After making a few pieces, I thought I should join a forum like this, to learn how to make them properly. So I understood. And, I usually don't use references or tutorials because I like to experiment on my own.
Thank you for your feedback anyways. I sure learnt something today.
Now, I go and delete the brushes I made.. 
Generally speaking, in my opinion (although I wish this was an international rule), it's better to put references and to be as transparent as possible about the creation process.
Again, in my opinion, using a brush like this doesn't qualify as pixel art, it's not controlled enough, so I wouldn't have accepted your other piece too. But that's my opinion (and I'm a hardcore purist). It doesn't mean I'm right. Everyone have different opinion as to where to trace the line.
If you look at the reference, I'm pretty sure you pixelated over a photography.
I think a reference should be used as a reference (to look at on the side) as opposed to tracing over.
Your avatar is a good example of creation, and to me is pixel art. You created something. You might have used a reference but didn't trace over anything. I much prefer that.
This looks like filter thing. I doubt this will make it. Do you have a wip or the reference picture?
It's just my opinion, don't delete anything if you don't want to. :)