As singer-songwriters go, my mom likes John Mayer more than John Darnielle. And that’s fine: Not that I agree, but, at 50, my mom’s impulse to take the easy material sung in that pitch-perfect, wooing wheeze over The Mountain Goats guy who sings in a barely inflected, nasal tone is something I can’t argue with.

Certainly, I hold that “Hast Thou Considered the Tetrapod”–“One of these days, I’m going to wriggle up on dry land”–says more about everything than “’83”–“If Heaven’s all we want it to be, send your prayers to me care of 1983”–but going for the hook that’s easiest to swallow is understandable, if not agreeable. And arguing with your mom about pop songs is for golliwogs.

As post-rock bands go, my mom doesn’t really know what the term means. Even if I were to explain that post-rock is a subgenre of indie rock where the basic instruments of the toolbag are redirected for more abstract purposes (which, I admit, shouldn’t qualify as a definition), she still wouldn’t know exactly what that means. I’m confident, though, that Stella Currin is a Mogwai fan in waiting.

On their fifth full-length, Mr. Beast, Mogwai–a Glasgow quintet considered post-rock pioneers for their ability to cull extreme dynamics created by guitar, drums, bass and electronics into arching, sublime crescendos–establishes itself as post-rock’s answer to adult-contemporary music. In a universe that now includes bands like Texas’ catharses-mustering Explosions in the Sky, New England’s protraction experimenters Bardo Pond, and Japan’s head-over-heels metal/drone/melody heavyweights Boris, Mogwai is John Mayer’s willing analogue.

Consider Mr. Beast, one of the softest “hard” albums I can recall. The name speaks volumes; something called Mr. Beast, in my purview, should romp through the ranks of M83, Cornelius, Pelican and Mono like an original Sasquatch back to reclaim its hierarchical reign over the forest of followers. After all, the thing was recorded in a place called The Castle of Doom, a studio the band just bought in Glasgow.

But, in talking to founder Stuart Braithwaite, he’s quick to point out that The Castle of Doom has windows, something uncommon for studios, stereotypical dens of despair, dimly lit and crowded, lined with amps and pungent with the pressure of finishing a record on time and on budget. Maybe it’s the light of day that affects this album, a case study in unsatisfying restraint, consistent coitus interuptus from a band that delights in talking about this album because they see it as a return to rock after 2003’s electro-pulse Happy Songs for Happy People.

But the sense of finality that one would expect from a rock album isn’t manifest here: piano-and-drum-march opener “Auto Rock” pushes it to the threshold, and it seems that the acerbic snarl of the guitars on follower “Glasgow Mega-Snake” will push Mogwai back to the glory of Rock Action or Come on Die Young. But it comes up short, and the rest of Mr. Beast seems low on ambition and impact. The pretty tunes are half-handed and noncommittal, open space for a band that’s never been as good at the inward gaze as they have been at the outward reflection, anyway. Even volume pinnacles like closer “We’re No Here” seem tired, despite its inclusion of the album’s best grating guitar heroics and way-low bass throbs, seem throttled back.

And it’s not that Mr. Beast is bad. It’s actually pretty good. But, almost a decade after Mogwai helped steer post-rock to new frontiers, it seems like a lukewarm repetition of its master’s past, an attempt to justify the electronic austerity of Happy Songs for Happy People in the context of the big bang rock music that made Mogwai one of the most important bands in indie rock. Frankly, M83 has made stuff like “Auto Rock” obsolete, and Explosions in the Sky makes the E-bow slinking of “Folk Death 95” with much more force. But, don’t panic: With a little remix (and perhaps some vocals), “Emergency Trap” could be on your local adult-contemporary format tomrrow. And my mom would totally call me at 7 a.m. to ask if I had heard of the band Mogwai.

Mogwai plays the Cat’s Cradle on March 8 at 9:15 p.m. Tickets are $15. The fantastic Growingopens.