I don't know, this isn't what I experience in high Silver nor is it what I see streamers experience as high as Radiant. Sure you do play against a reasonably big spread of ranks, but not even the streamers I watch have to get MVP every match to stay there. Instead while you do need a solid performance when you play against people consistently below you, often you will play against people above you too. Besides, the ranks seem to relatively accurately reflect skill level which tends to be reflected in the combat score ratings by the time you finish the game. Sounds to me as though you may be either:
A) Playing too much with lower ranked friends where you will almost always be the top dog and expected to have a reasonably good performance, or
B) Stuck in a region without a big enough player base to have enough people at your rank, I'm not sure where though, maybe South America?