Matt Brown was overhyped the guy hit hard but he didn't like getting hit and his ground game isn't good at all of his 6 losses 5 are by submission. Also the level of fighters fighting in Amateur MMA is often very low. His submission aren't very fluid at all.
And while his submission are good enough to catch the guys he's faced so far they aren't good enough to catch UFC level fighters. His stand up is probably good enough to hang with above average UFC strikers but he doesn't have the wrestling to keep fights on their feet. Look at what Gerald did to him CB is 10 times the wrestler Gerald is.