Oscar Predictions: Best Original Screenplay

It's time again for the Oscars. It's been a long Awards season as always. Guilds, Globes, BAFTAs, and critics have all made their picks  and I'm here to figure out what it all means. Yes, it's time again for my multi-part Oscar predictions.
I'm going to go through each category, tell you who has been nominated and won for what, give a context for what that means, and order the nominees from most to least likely to win on Oscar night. That doesn't mean I'll be right, but it does mean I'll be informed. Wish me luck.

Previously:
Nomination Reaction
Documentary, Animated, and Live-Action Short
Documentary Feature
Animated Feature 
Foreign Film
Visual Effects
Sound Mixing and Sound Editing
Makeup & Hairstyling 
Costume Design
Score and Song
Production Design
Cinematography
Film Editing
Adapted Screenplay
Original Screenplay
Supporting Actress
Supporting Actor
Lead Actress
Lead Actor
Director
Best Picture

Glossary:
BAFTA - British Academy of Film and Television Arts Awards
Golden Globe - Presented by the Hollywood Foreign Press Association  Award
WGA - Writers Guild of America Award

The story is very much the same with the Original Screenplay award as with the Adapted Screenplay award. It's hard to tell much, even with a clear front runner. That Golden Globe win for Steve Jobs made the Globes pretty useless this year. They have at least nominated the Oscar winner in this category 18 times in the last 20 years though. So have the BAFTA. They've only matched winners with the Oscar 10 times. The WGA isn't helpful at all. Three of the last five Oscar winners for Original Screenplay weren't even eligible for the WGA award. The other two times, the WGA winner did win the Oscar as well.

Spotlight
BAFTA - Original Screenplay - Winner
Golden Globes - Screenplay - Nominee
WGA - Original Screenplay - Winner
It's the only of the Oscar nominees with a win between the BAFTA, WGA, and Hollywood Foreign Press Association. I have to believe that Spotlight is still in the thick of the Oscar race and it needs this win for me to believe it has the necessary support.

Inside Out
BAFTA - Original Screenplay - Nominee
WGA - Ineligible
Pixar has never won an Original Screenplay Oscar. How crazy is that?

Straight Outta Compton
WGA - Original Screenplay - Nominee
After the OscarSoWhite controversy, I'd wonder if that gives Straight Outta Compton a leg up in its only nomination. The fact that it was written by two white people probably lessens that push though.

Bridge Of Spies
BAFTA - Original Screenplay - Nominee
WGA - Original Screenplay - Nominee
It's a double nominee. That can only help.

Ex Machina
BAFTA - Original Screenplay - Nominee
I just don't see it. Not enough broad support or other screenplay nominations for it.