those of you guys wondering hhow you know when you're close to a blue, this is how my coach does it.
He'll pull me aside, and say, I want you to roll with x, and don't go easy. I know straight away he's seeing if this guys ready. I wn't go easy but I'll really push these guys. If he's holding his own in these conditions then it doesn't suprise me if he comes in a few days later with a new color.
Speaking from a mid level blues perspective, I have no doubts about the purple's abilities when I'm beating them. I've seen some of these guys tear up browns in competitions.
Watch some of the blues you think you're beating in a comp. See if you notice the difference in intensity.
That said, a lot of guys roll hard all the time. And it can be hard to tell people's level. There's a new guy who just recieved his blue, and I know at least 5 white belts who I think are way, way, above his level (and a few other blue's level too for that matter)
It sounds bad, but I've also noticed guys that the coach doesn't get along with seem to have to wait longer to get stripes/belts.
That said I've only had my blue for about a year and a half, so I'm still a beginner. Just comments from my observations