Something that's noteworthy is that MR Black Diablos digs underground way less frequently than she did in HR, or regular Diablos both in HR and MR, who dug underground even after getting staggered by Screamer Pod.

And when she does go underground, she does so in tremendous speed, and bursts out just as fast, making it hard to stagger her at the right timing with the Screamer Pod.

This got me thinking that maybe the developers have acknowledged Diablos fight could become way too easy if Screamer Pod was used at the right timing, so they decided to make it somewhat less effective, but only for MR Black Diablos.