Earlier this year, Deep Purple were inducted into the Rock and Roll Hall of Fame, after having been nominated twice before, and ignored for over two decades (they were eligible since 1993 and their exclusion was one of the more famous digs at the Rock Hall's credibility). Questions like "why now?" and "how did Aerosmith get in 15 years before Deep Purple?" may never be answered, and a better question may even be "does anyone really care what the Rock Hall thinks?" Still, something about them finally getting inducted feels like a big deal.

The Hall of Fame's long-running diss against the band makes you wonder if the Hall isn't the only place Deep Purple appear less crucial than they really are. It does indeed appear that way. Ask your average music fan under 40 about Deep Purple. They may just tell you it's the band with the song every beginner guitarist can play. Maybe they realize this is also the band who wrote "Highway Star," but the rest of Purple's rich history often feels silenced. They've been frequently grouped with Led Zeppelin and Black Sabbath as pioneers of heavy metal, but while those two bands remain wildly popular and their importance is reinforced again and again by critics, the same can't really be said for Purple. Just look at forums like this one: "Is Deep Purple No Longer Considered Part Of The Evolution Of Heavy Metal?". It's eight pages long and the verdict is pretty split. More obscure groups like Blue Cheer and Pentagram seem to get the "heavy metal pioneer" title more often than Deep Purple. Classic rock radio isn't exactly doing its part either. They play "Highway Star" and "Smoke on the Water", but if one of those stations would play "Speed King" even a quarter of the amount of times that they play "Hotel California," there still might be more room for some new perspective on the talked-about-to-death '70s.

Black Sabbath remain a stadium band. If Led Zeppelin would reunite, they'd obviously be one too. Not to act like Deep Purple have as many hits as Coachella 2015 headliners AC/DC (who still had Brian Johnson and Cliff Williams at the time), but what a low blow that Deep Purple's own trip to Indio, CA last year was to play a casino.

That's all even weirder when you consider their current live lineup is actually in pretty good shape. It's almost the entire MK II lineup -- the lineup that was responsible for their three most classic albums -- except organist Jon Lord who sadly passed away in 2012 and guitarist Ritchie Blackmore, whose current relationship with the band is so rocky that their manager wouldn't even allow him to attend the Rock and Roll Hall of Fame induction ceremony. No Blackmore is the obvious downer -- his riffs are arguably the most essential part of Purple's sound -- but it shouldn't take away from the amount of legendary talent that's still on stage.

Not to suggest that Deep Purple aren't selling a lot of tickets when they're playing secondary markets. In fact, a band like Pentagram is probably selling less tickets at their shows. But by playing cool youth-targeting festivals like Meltasia, Psycho Las Vegas, and Burger Beach Bash and touring with hip modern bands that they've influenced, they're securing their legacy with younger generations (even if that's not all a positive). Deep Purple seem like they're at risk of becoming a relic, if they haven't become one already.

My own relationship with Deep Purple goes back to childhood. They were actually my first rock concert, though I was too young to remember anything other than that it was very loud and that I fell asleep during their set. It was the 1998 tour with Emerson Lake & Palmer, and my dad took me to the Jones Beach show. There was a third band, but we stayed in the parking lot for their set because my dad said they sucked. Years later I learned that band was Dream Theater. My dad never steered me wrong.

I couldn't have known it then, but I'd see the light of Deep Purple's masterpieces down the line. Like a lot of people, I first knew "Highway Star" and "Smoke on the Water", both off 1972's Machine Head, but it wasn’t until years later that I’d discover their less played, more groundbreaking material. 1970's Deep Purple In Rock, the first album with the MK II lineup -- which had Blackmore and Lord plus founding drummer Ian Paice and then-new members Ian Gillan (vocals) and Roger Glover (bass) -- still sounds shockingly ahead of its time today. Released the same year as Paranoid and Zeppelin III, Deep Purple In Rock predicted the future of heavy metal in ways not even those albums could. Ozzy was more evil and Plant had better range, but neither of them screamed like Ian Gillan did. He set as much or more of a precedent than Plant and Ozzy did for guys like Rob Halford and Bruce Dickinson. Sabbath and Zeppelin both got fast, but "Speed King" is to speed metal what "Sweet Leaf" is to doom. You can just picture a young Lemmy hearing it and finding inspiration.

In Rock also justifies anyone calling Blackmore a guitar god. The noise that introduces "Speed King" must have sounded like a huge "fuck you" to Deep Purple's MK I period when this record came out, and all the riffs and solos that follow in the next 43 minutes leave you wondering just how the hell "Smoke on the Water" is what people wanna remember him for. That MK I period, by the way -- which had Rod Evans on vocals, Nick Simper on bass, and produced three studio albums -- had Purple functioning as a straight-up psychedelic rock band, like a lot of proto-metal bands were at first. That sound is almost entirely gone by In Rock, save for "Child In Time," which is essentially a jam on "Bombay Calling" off the first album by It's A Beautiful Day, a highly underrated band from the same San Francisco psych scene that produced the Grateful Dead and Jefferson Airplane.

Elsewhere on In Rock, there's the early stoner rock of the murky "Into The Fire," more noise and heroic solos on "Bloodsucker," and still plenty of other stuff that still feels fresh today. Then there's the 1971 followup, Fireball, with its opening title track that rivals "Speed King" as far as essential early speed metal goes. This album's also got "Anyone's Daughter," an outlier and the only time you might call MK II-era Deep Purple "Dylanesque." It's also got the iconic "The Mule," which could get extended to ten minutes at live shows (with a lengthy drum solo), as you can hear on the band's must-have live album Made In Japan.

Fast forward a few years, and Deep Purple's MK III lineup debuts with 1974's Burn. In place of Gillan and Glover, they've now got David Coverdale on vocals and Glenn Hughes (of the psych/prog band Trapeze with future Judas Priest drummer Dave Holland) on bass/vocals, introducing a dual-vocal style to Purple's sound. Coverdale would get a lot more famous a few years later by forming the hair metal band Whitesnake and churning out cringe-inducers like "Here I Go Again." But his (ongoing) hair metal years are forgiven when you consider he was making real-deal heavy metal before most bands were. (Maybe even Coverdale looks back more fondly on his Purple years -- Whitesnake's latest album, 2015's The Purple Album, is all Deep Purple songs, and he's planning a live album/film of the tour he did in support of it.)

Burn came out the same year as Judas Priest's first album, but even that was more of a traditional hard rock record. Today, the wailing vocal harmonies of Burn's opening title track could fool someone into thinking they're listening to early '80s NWOBHM. (Deep Purple really know how to pick opening songs.) Coverdale and Hughes' vocals really introduce a new life to the band, and it doesn't hurt that Blackmore and Lord are at the top of their game here too. It's truly classic heavy metal. Another album (Stormbringer) would drop later that year, and then Blackmore would leave Deep Purple, team up with some guy named Ronnie James Dio from some band called Elf to form the band Rainbow, and explore the Burn sound even further.

Like Sabbath (but unlike Zeppelin), Blackmore fully embraced the "heavy metal pioneer" title and continued to innovate the genre as it gained popularity with a slew of bands he himself influenced. Those first three Rainbow albums are crucial heavy metal albums. I might even argue that they’re a little more highly regarded by metal audiences today than Deep Purple albums, but that’s probably more thanks to Dio than to Ritchie Blackmore. Unlike any band Blackmore ever played in, Dio was voted one of the 25 best metal bands when MetalSucks polled 100+ musicians/critics/industry folk in 2014. AC/DC, who of course influenced metal but were never really a metal band themselves, make the list. Even… Lamb of God does. (Obviously Black Sabbath are #1, and Ozzy is on there solo too.)

Speaking of, an interesting plot point that anyone who's read this far probably already knows: After Dio left Rainbow (who had 2 members who went on to form Bible Black with future members of Blue Cheer and Anthrax), he replaced Ozzy in Black Sabbath and did two classic albums with them. Once Dio left Sabbath, he was replaced by Ian Gillan for one album. Then Gillan left, and Sabbath's next album had Glenn Hughes on lead vocals. The only Sabbath member that appears on all of those releases is Tony Iommi. How often do two major guitar-hero rivals also work with three of the same singers?

Deep Purple's rich proto-metal history may be written off in part because of the novelty of that "Smoke on the Water" riff, but they aren't the only band with this fate. Take another colorfully-named band Blue Oyster Cult, a band where you risk being told something about cowbells anytime you bring them up. "Burnin' for You," and to a lesser extent "Godzilla," are still classic rock radio staples, but they tell so little of the band's story. A major difference between Deep Purple and Blue Oyster Cult (besides that BOC are still not in the Rock and Roll Hall of Fame), is that while "Speed King" or "Burn" trump "Smoke on the Water" any day, "(Don't Fear) The Reaper" and "Burnin' For You" really are BOC's best songs. Also, neither of them are metal songs. "Reaper" lives on because of its iconic guitar arpeggio and lush '60s-recalling harmonies, and "Burnin' For You" is new wavey power pop. (Both also make use of the ever-addictive Am-G-F chord progression that has never failed at making a rock song lovable. Just ask "Hey Hey, My My" or you know, "Stairway to Heaven.") But really Blue Oyster Cult were never very metal anyway -- they had evil imagery (like the umlaut over the "O" in their name and the cross in their logo) and sometimes evil sounds, but they weren't a very heavy band. That's why now they often get namedropped when people talk about Ghost. That's not a knock though. Looking cool is a really important part of rock and roll and don't ever let anyone tell you otherwise! It does matter that BOC looked evil before zillions of evil-looking metal bands formed.

Blue Oyster Cult's heaviest record is their 1973 sophomore LP, Tyranny and Mutation, a nice slice of early stoner rock, but nothing that Sabbath or Purple (or Budgie or Uriah Heep) hadn't already out-heavied. Their most important album to the development of heavy metal though, is that album's 1974 followup, Secret Treaties. It may not be a very heavy song, but the devil-ish chord progression and truly evil vocals on album opener "Career of Evil" predicted metal's popular era more than the louder Tyranny and Mutation. Add some thick distortion to that song and it wouldn't be too out of place on a Judas Priest album, or maybe like, a Diamond Head album. (Not to mention Patti Smith -- who was dating the late Allen Lanier of BOC at the time -- wrote the lyrics to that song, and other songs throughout BOC's career. How cool do you have to be to collaborate with Patti Smith?) "Subhuman," "Harvester of Eyes" and "Astronomy" offer another glimpse into the devil's lair.

Patti Smith's contribution aside, there's some proto-punk on this album too. "Cagey Cretins" sorta sounds like a slightly more evil Stooges (whose Iggy Pop would go on to collaborate with Allen Lanier). "Dominance and Submission" makes you wonder if the Ramones had it in mind when they wrote "We're A Happy Family" the same year they opened for Blue Oyster Cult.

After Secret Treaties came 1976's Agents of Fortune, home of "(Don't Fear) The Reaper" and the band's best album. Opener "This Ain't the Summer of Love" is more BOC-style evil and a clear heads up that this band is no bunch of flower-power hippies (even though, again, "Reaper" has those harmonies that beg to differ.) That song aside, BOC really aren't much of a proto-metal band anymore at this point. Patti Smith returns, this time not to just to co-write but also to sing on "The Revenge of Vera Gemini," and that song is not surprisingly a highlight. There's some more hard rock on this album ("True Confessions," "Sinful Love," "Tattoo Vampire"), but the band's days as a prescient heavy metal band are mostly behind them by 1976. It’s the year Judas Priest set a new bar for heavy metal with Sad Wings of Destiny, and Agents of Fortune’s hard rock songs sound dated in comparison.

Blue Oyster Cult are sometimes lumped in with washed-up baby boomer bands, but they've been popping up in hipper modern-day circles too. "Reaper" turned 40 this year, and the band's tour in celebration of that hit NYC for a residency at BB King's, where classic rock is usually represented by the current lineups of Asia or America or Foghat. (For comparison, the back-in-action Grim Reaper hit Brooklyn's home of underground metal, Saint Vitus.) That said, the very cool Psycho Las Vegas festival -- which also booked Pentagram -- had them repping proto-metal along with Alice Cooper and obscurer bands The Crazy World of Arthur Brown and Truth & Janey. Pitchfork also put "Reaper" on their recently-published 200 Best Songs of the 1970s, a list which does not include "Stairway to Heaven" (or anything by Ritchie Blackmore). How's that for revisionist history of the '70s?