Any advice on mixing piano so it sounds natural ?

Hello! I recently made song that features piano and electric guitars. My problem is that many people told me, that piano doesnt sound natural/is not mixed well/sounds robotic. I recorded piano parts in reaper DAW using neo piano plugin and midi keyboard. What could be improved on when it comes to mixing and playing ?
Here is song im talking about:  

It's ok as a piece but what's a natural sounding piano? I think you should address that question to your detractors. All pianos are slightly different usually by brand and whether upright or grand but unless tinkered with sound like pianos. They can encompass a huge range of music. If this one sounds robotic to them, so what?

Perhaps their expectations are different. I heard a vibrant, energetic song that sounds perfectly well mixed. The instruments seem well differentiated, balanced.

A piano sounds robotic because it's not played by a human, not because of the mixing.

I played it on midi keyboard, maybe i corrected it too much so it sounds "too perfect". 
Now that i think about it, propably should play around with velocity of certain notes !

Yeah, the issue is definitely that the velocity and timing of the piano is too rigid.

The most important thing to remember when people talk about problems with "mixing" is that 99/100 what they're talking about has nothing to do with mixing.