During my second sighting of DOTM and I swore I would keep an eye out for Sideswipe and listen to his lines whenever he was nearby, I noticed that, after Ironhide had died, Sideswipe was doing something I wasn't expecting... He was giving out orders to the other Autobots when Optimus wasn't around! To prove this, during the scene when the Autobots were hiding in the building after Optimus lost his flight tech and Wheeljack had given out boomsticks and grapple gloves to the humans, Sideswipe ordered Wheeljack to get moving. Sideswipe did this again when they were battling against the Decepticons before their capture. He did it one last time by ordering the Autobots to help Optimus. I don't know if it was a human ordering this, but my ears never lie. So, I think Sideswipe had been given the title of second in command by Optimus Prime offscreen. Whether or not this is true, we won't know until we see it again or it comes out on Blu-Ray/DVD. I'm just telling you what my ears heard, that's all.