Metal Insider’s Top 5 is a column where we count down the top five of…well basically anything.

We’re coming close to the end of another year. Soon Metal Insider’s contributors will be revealing their favorite albums from the past year. However, in addition to a lot of great music being released, 2011 also had its fair share of events no one saw coming. Some gave reason for fans to rejoice, while others were downright unfortunate. So with that in mind, we decided to list the top 5 moments of 2011 in metal that surprised us the most.

5. Chimaira’s Rotating Lineup

Unfortunately, 2011 saw many bands parting ways with key members. But Chimaira’s lineup problems arguably stand out. At the beginning of 2011, Chimaira found themselves without keyboardist/ programmer Chris Spicuzza and drummer Andols Herrick, while bassist Jim LaMarca had left the group just before the end of 2010. Things were looking up for Chimaira following the additions of Daath singer  Sean Zatorsky (on keyboards/ sampler), Daath guitarist Emil Wrestler (on bass) and drummer Austin D’Amond (Bleed The Sky, The Elite). Plus, the band had unleashed a new album The Age Of Hell in August. Then fans were hit with a bombshell: the departure of guitarists Rob Arnold and Matt DeVries (who will be officially leaving the band following the annual Christmas show). It’s certainly been a bitter year for Chimaira fans.

4. Worship Music Is Actually A Great Album

Anthrax had the deck stacked against them when coming out with their first album in eight years. First of all, even though We’ve Come For You All came out in 2003, it really had been since 1993’s The Sound of White Noise that they were at their most popular. It didn’t help that the album was recorded with the band’s new singer Dan Nelson, then scrapped once he left the band. And bringing back Joey Belladonna, their most popular vocalist, after sacking him twice seemed like a hail mary move of desparation on both Belladonna and the band’s part. Surprise, indeed. This is by far the band’s best album in years. Songs like “The Devil You Know,” “Fight ‘Em Till You Can’t” and “I’m Alive” fit in alongside their best material. And the band’s killing it live, rightfully standing proudly alongside Metallica, Slayer and Megadeth as part of the Big 4. The only real surprising thing is that they weren’t nominated for a Grammy for Metal/Hard Rock. We’ll blame Sum 41 for that.

3. Metallica’s Unlikely Collaboration

When Lou Reed joined Metallica at the 25th Anniversary of the Rock and Roll Hall of Fame, it was an interesting one-off. Who knew that they would take that and run with it? When Metallica announced they were working on something special, no one would have guessed the end result would be Lulu, a self-indulgent double album based on the plays of German playwright Frank Wedekind that tried the patience of fans of both acts. You can’t blame either Lou Reed or Metallica for wanting to stretch artistically, but they can’t be surprised that the public didn’t bite. The real winner of this? Morbid Angel, whose Illud Davinum Insanus was a lock for worst album of the year until Lulu was released.

2. Black Sabbath Confirm Plans To Record New Album

Let’s face it, even with the back and forth reports from Tony Iommi, it was pretty much a given that Black Sabbath’s original lineup would reunite for a tour eventually. What was a surprise to hear during the press conference, though, was that Black Sabbath would be recording a new album with producer Rick Rubin. Furthermore, the band stated that they are hoping to release the album sometime in the Fall of 2012. Granted, there’s always the slight chance that recording can be delayed, and let’s not forget that the four tried to work on a new album with Rubin in 2001 before Ozzy had to get back to his solo career. At the same time, though, it was a nice surprise to hear that Black Sabbath were at least attempting to record new material. And this time, it sounds more like a sure thing.

1. The Year Bassists Went Bonkers

Bassist Mic Todd left fans in shock when he was arrested for attempting to rob Oxycotin from a Walgreens in Massachusetts with a fake bomb just before Coheed And Cambria were to take the stage. The incident, unsurprisingly, lead to Todd’s departure from Coheed And Cambria for the second time. Then, when everyone thought no one could top Todd’s public arrest, Kyuss Lives!/ ex-Queens Of The Stone Age bassist Nick Oliveri was arrested following a four hour standoff with a S.W.A.T. team. And though he still may face a large amount of jail time, Kyuss Lives! decided to stick it out with Oliveri. Both bassists’ past issues may have been well documented, but their public meltdowns this past Summer still came as an enormous shock to everyone.