Every year when the Oscar nominations are announced, there's general grumbling about movies that were left out — usually films at either end of the Hollywood spectrum, the biggest blockbusters and the tiniest art films.

But the people doing this grumbling often don't understand that the Oscar nominations process is somewhat designed to yield bland, consensus nominees. There are a few ways that bold artistic statements can sneak in, but it's much harder than it is to be nominated as a film that a lot of people like well enough.

Let's take a look at why this is.

Some voters' ballots for Best Picture nominations are counted twice

Best Picture is the only award voted on by all 6,291 Academy members at the nominating stage. And a movie only needs to grab a little over 5 percent of the voting body to crack the Best Picture lineup. That means smaller movies with cultlike fan bases can get in with just over 300 votes. (This also arguably hurts some of these movies — artier choices often have a smaller pool of voters to choose from in the first place.)

Of course, it's also hard for those films to win. "A little over 300 votes" won't get you anywhere in a "winner takes all" race. But still, as my colleague Alex Abad-Santos has pointed out, there's more of a monetary benefit from being nominated than there is from being a winner, so these nominees will likely take what they can get.

Let's dig more into the nominations process.

Best Picture is the only category where nominees are voted on by the entire Academy. The Best Picture lineup has at least five final nominees and no more than 10. Votes are tallied by accountants over two rounds. Up to 10 films that have garnered at least 5 percent of the vote are nominated. Except, as with all things at the Oscars, it's slightly more complicated than that.

Here's how the Oscars have modified instant runoff voting for the nominations process.

1) Academy members vote for nominees

To qualify for the Oscar ballot, a film must have played for at least a week in Los Angeles County in the calendar year being considered. That describes a lot of films (305 for the 2016 awards, which recognize films that came out in 2015). Academy members are asked to vote for at least one and up to 10 Best Picture candidates, ranked. (For simplicity's sake, we're going to assume all 6,291 Academy members ranked at least a few choices.)

2) The first round of counting and the first threshold

The accountants separate the ballots by first-place votes. Every film that crosses a certain vote threshold is added to the Best Picture lineup.

That threshold is the total number of voters (in our example, 6,291) divided by the total number of potential nominees plus one (11). That's more than 571, which is rounded up to 572. (This works out such that if 10 films get 557 votes, the 11th film won't make the list.)

The process can stop after the first round if 10 films make it in, but that's unlikely.

Some voters' ballots are counted twice

3) The surplus rule

Now the accountants turn to the so-called "surplus rule."

The "surplus rule" means that any voters who supported a film that crossed the threshold plus 10 percent effectively get their ballots counted twice. In our example, this number is 629 or higher (572 + 57 = 629). All voters who voted for a film that triggered the surplus rule sees their ballot counted a second time for their second-place choices (though these votes count for slightly less — we don't know how much less). I'll say that again: Some voters' ballots are counted twice.

4) The 1 percent rule

In addition, the accountants remove any ballots whose first-place choices appear on fewer than 1 percent of ballots. This is the standard instant-runoff scenario, where voters' first-place choices failed to garner the requisite amount of support so their second-place choices are now counted instead.

5) The second round of counting

The votes get tallied again. This time, the threshold is lower. Any film with 5 percent of the votes or more makes the list — up to 10 films total. The threshold number thus drops from 572 (the threshold determined in the first round, which in this case is a little over 9 percent) to 315 (slightly over 5 percent of the 6,291-member voting body).

6) The unlikely third round of counting

If there are fewer than five films in the Best Picture lineup at the end of the second round, things could proceed to a third round, but this seems staggeringly unlikely.

How the nomination process works

Let's look at the 2015 Best Picture lineup to see how this all might have shaken out.

Say Boyhood received 1,000 first-place votes, Birdman 900, The Imitation Game 800, and The Grand Budapest Hotel 590. That would put all four films past the 557-vote threshold and into the Best Picture lineup.

As round two of counting begins, the ballots for all first-place choices receiving less than 1 percent of the vote total are once again considered, starting with the second-place choices. Then the surplus rule kicks into effect, tossing all of the ballots with Boyhood, Birdman, and Imitation Game in first place back into play. The Grand Budapest Hotel falls 23 votes short of 613. Ballots that have it in first place remain out of the second round of counting.

After our reallocation, let's imagine The Theory of Everything now hits 600 votes, while American Sniper gets 450 votes, with Whiplash and Selma scoring around 330 votes. The accountants check the first-place choices to see which additional films cross the 5 percent threshold. All four films do — and join the others for the final Best Picture lineup.

Differences with other categories

Meanwhile, in the other categories the same system applies, except it goes on until five nominees (or three nominees, for some) make the list, and the surplus rule is triggered by a contender receiving the threshold number plus 20 percent.

The threshold number for the designers is just 19

Unlike Best Picture, nominations in other categories are only voted on by members of the particular branch of the Academy they fall under, like the acting branch or the designers' branch. (The threshold number is often perilously low for these branches — for the costume designers, it's just 20, according to the Wrap.)

When it comes time for voters to choose Oscar winners in early February, all categories are voted on by everyone. Thus, only experienced directors of photography choose the Oscars' nominees for Best Cinematography, but the entire voting body chooses the actual winner you see accept the prize at the ceremony.

The nominations process has benefits

As mentioned, it allows the Oscars to let some offbeat choices slip into the lineup. If you can get 315 people to rank you in first place, you're in the Best Picture race. And once you consider that it's almost certain not every one of the Academy's members votes, the task becomes even easier. Thus, a movie with a passionate cult, like The Tree of Life or Amour, can make it into the Best Picture lineup.

But the simple fact of the matter is that the Best Picture nominees lineup is ultimately just a bunch of first-place choices — and likely a handful of second-place choices — from Academy members.

And although this system benefits more cultlike films, it has the inverse effect of punishing movies that people are less likely to rank in their top two slots — like, say, blockbusters. You can imagine a scenario in which every single Academy member ranked, say, Guardians of the Galaxy in third place on their ballots for nominations, meaning it would be highly unlikely to receive a single vote for Best Picture, despite being arguably one of the three most popular films of the year.

That system also makes it far easier for more challenging, artistic work to rise (since it is chasing a smaller pool of voters), in favor of largely bland and inoffensive choices, which are more likely to land in second place on various ballots.

In essence, at every step of the Oscars process, the voting skews results toward bland consensus, rather than smaller, nervier choices. That hasn't yet completely overrun the nominations process, but it sure seems to be turning out bland winners.