The feedback I got for my portion of Project 1 from last week's session was to fix the shadows on the ball so they aren't as black and match better with the shadows in the background plate, add some dust to my shader on the cannonball so it looks like it belongs with the background and the dust effect, soften the edge of the shadow on the ground a bit, and add motion blur.
The above picture in the left is my grey ball match compared to the photo I took as part of the set. I adjusted the shadow radius a little bit to soften it as it got longer, but I didn't want to push it too far because the shadow is quite sharp in the reference photo.
The video above is a turntable of my updated shader. I added a layer of dust and tried to match the color of the cement in the background plate so it feels like it belongs in this setting. I also adjusted the amount of bump in each layer of the shader as well: the shiny metal, the dust, and the dark rough metal.