I really dislike the ground texture you used in screenshots 3 and 4. it would look fine in small amounts, but that over and over and over makes my eyes hurt. Also, it looks like you really need to build cubemaps. i can see purple and black checkers in screenshots 2 4 and 5.
Okay gameday result:
Fail cubemaps
Fail swamp props
Raise spawn rooms
Redirect teams towards CP more
Limit building placement
Add some playerclips