hmm, maybe try to use the BURN/DODGE technique boubabi showed me
u create a new transparent layer over the render, select the pixels of the render, paint it grey, and set it to overlay (which I think I explained above) but THEN you take the BURN/DODGE tool (i think BURN is the one that darkens) and 'paint' on that grey overlay layer you created, to make the shadows darker, and then u can use DODGE to make the light areas lighter)
See how on the sig you linked that u were emulating, the render's contrast between light & shadow is very pronounced. His head/shoulders clearly show light reflecting, while his body, for the most part, is much darker.... I can sort of see this on your sig, but the body of the hockey player render is still way too bright.
Also, the 'text' on the sig you were trying to emulate is wayyyyy more advanced than you would think. it looks like it's at least 2-3 text layers PER line... Some of which were set to overlay or maybe hard light or something, to get it that effect (whereas yours just looks like one text layer alone, i think)
Finally, I think in the emulation sig, his background makes good use of BLURRING to give it depth, some of the layers appear to have been gaussian blurred, whereas all of your background layers are not, which makes it kind of appear to all be on the same 'level' (in terms of depth). Maybe gaussian blurring some elements of your background, along with making the right/bottom/left edges much darker (almost completely black, like the reference signature) could help it.
ultimately tho, I have no idea im just making suggestions