It depends how you draw the line between "hit" and "decent". Surely both Fletcher and Brown were good player, for Brown case despite being massively rated, his career didn't quite end up as good as his hype as "England most talented defender", he was never really first choice key defender for us, maybe he has 1 or 2 very good season, but it didn't last long enough, as back then we have well established back four of Evra Rio Vidic Neville, he was more like a squad player or backup for us. For Fletcher case, its similar, he was very hyped as a youngster, I was kind of expecting him to carry our midfield in future in similar way Carrick does for us, but most often his Man Utd career was more remembered as a useful squad player rather than key player for us, and just when he was about to established himself as key midfielder for us, his career with us end prematurely with some serious illness unfortuntely. For me, both of them could have done more for us, but didn't go as far as they were hyped, but neverthelss still end up having decent career with us.
Cleverley was not hyped as a youngster, but at one point he was hyped when he became our first choice midfielder. Maybe he created his own hyped, but Fergie did trust him enough to give him many starts at one point.