You see how all but one of your images has blue sky in it? the sky is pink where the sun is, but not the entire sky.
Mobster's is monotone pink, which also isn't like any you posted.
When the sky gets crazy colours in it, they're always concentrated around the sun itself, if you look 90 degrees and 180 degrees away from the sun you'll always see noticeably different colours. Not in mobster's.
I'm opposed to two things:
1) Mobster's is just monotone pink, with zero blue or variation in it anywhere.
2) That pink is artistic murder. TF2's colour palette just does not allow for such vibrant pink, it just doesn't fit with existing TF2 elements OR work well on it's own, the images are just a wash of pink.
I am not trying to say he shouldn't try out a new thing, or that he shouldn't deviate from the colour scheme of TF2. What I'm trying to say is that how he's done both of those things is really bad. the colour palette he's created is one single, vile colour, and ignoring that, the sky is super bland and not at all how the sky behaves (I mentioned the sky should be different colours in different directions already).
EDIT: Find me an un-photoshopped 360 degree image of an ENTIRELY monotone pink sky and I'll back down on that point. The second point would still remain however.