1st one:
1. The render is way to blurry, try sharpening the render more so it stands out.
2. The text doesn't match the sig, maybe different fonts and effects to make it blend more.
2nd one:
1. The render doesn't blend in with the BG, try smudging a bit around the render.
2. That light spot on the right side is very distracting, you should have put it in the middle (above his head)
3. Text could be a bit smaller, also a bit distracting.
4. Blur the BG a bit more, the render doesn't stand out as much as it should.
~Inferno