The important thing to notice about dragoon compared to Monk is Blood for Blood. On Monk, that's a 10% damage boost. For Dragoon, it's 30%.

What this means is that every time we get a crit under B4B, that crit is an extra 30% stronger than if we got that same crit out of B4B, compared to the Monk's crit swing being just 10% different in and out. If you get super lucky and crit every hit under B4B (read: why we stack Battle Litany and Internal Release for our opener under B4B) it's a HUGE gain compared to getting that same luck just after B4B falls off. Since I'm curious, I'm actually gonna run the numbers to compare the difference between getting a crit on EVERY HIT under your initial B4B to getting a crit on the entire 24s rotation that follows, not including OGCDs or dot ticks.

http://puu.sh/kVx68/e341378da6.png

Of course, it's not perfect, but you can see that in a case where RNG haaaates you, you're gonna pull substantially lower than in a situation RNG loves you. I also chose to assume you flubbed and forgot to Life Surge your first Full Thrust for the sake of widening the gap, since this is intended mostly to show the huge disparity you get from crits in B4B compared to crits out of it. And to draw a comparison between how it shakes out with a 30% B4B compared to the 10% MNK has:

http://puu.sh/kVxbn/d8c1cb0f2d.png

That's the main reason DRG's numbers are less consistent (or, better put, more sporadic) in short bursts than a class like MNK that doesn't have nearly as strong burst out the gate. And looking at this, just imagine how Bards look, with their Hawk's Eye / Raging Strikes / Blood for Blood all active on the pull. Imagine how much they cry when RNG decides not to give them crits there...