For 4 points? Awesome.

How can both the Blue and Yellow rings be both 4pts when one is clearly more useful than the other?

How is one more useful than the other? In my opinion, they are 100% identical. Sure one lets you perplex only up and one lets you only perplex down, but at the end of the day what is the difference if I perplex your defense down or my attack up?

Not identical in the slightest.

perplexing down someones defense will allow your whole team to take a whack at your opponents modified defense.

where as if you perplexed your guys attack up 1, that guy is the guy whacking with a modifer.

and likewise If you perplexed your own defense...

Agree that they're not identical, but they're two very different kinds of useful... As pointed out, allowing you to -1 someone's defense is a benefit to your whole team. However, one thing that Sinestro Corp Ring can't do is modify the amount of damage done to an opponent. Blue allows you to modify your damage - which is a great help.

I thought perplex went away after a dial change? So if that first attacker hits the lowered defense, the perplex goes away?