Here's a crazy idea I had just recently. We know Shockwave can change his form right? What if the heavily injured Ultra Magnus we see at the end of "Where is thy sting" isn't ultra magnus at all, but Shockwave in disguise? The reason he doesn't have his hammer is because the real UM has been kidnapped and taken somewhere. Shockwave is now once again firmly embedded within the Autobot power structure, but now even higher than before. Unlikely, I know, but Interesting.