I will be seriously disappointing if Oliver doesn't end the season as the actual bad guy. Reasons below.
He's the mayor. He's the reason Rene didn't get to see his daughter back in S5. Oliver was funding protective services.
Dragon is ineffective.
He enjoys killing people, and should be considered a mass murderer. We all know it. Chase DIED for this.
It's the only way to keep the rest of the cast from looking like total fuckwits. It's a lot easier to excuse them repeatedly dragging down one character if they're reacting to a nagging suspicion that Ollie's doing something wrong.
Picture this: Oliver calls them all to the cave to address what's going on behind the scenes.
Grumpy Ollie: "You were all close, but the best prize goes to... Dinah ."
BANG "for realizing the corruption in the police department. Now, let's get to those runner ups..."