Blackout was supposed to be Soundwave in an early draft of the script. That's why he has an animalistic partner, and has been confirmed several times by Don Murphy on his boarRAB. Roberto Orci said on the official site boarRAB that Scorponock was originally going to be Ravage. That was scrapped to try and make Soundwave more like his old self by having the transforming boombox, but that it would transform into a human sized robot to avoid having mass-shifting, but the Helecopter remained and went through several different identities (first Vortex, another helecopter Transformer from 1986, then Incinerator, finally Blackout).
However, the transforming boombox went down like a lead balloon online, so they decided to try and mittigate the damage by "saving" Soundwave (ie putting him off to a possible later film in the hope some kind of solution would occour to them), and renamed the character "Soundbyte". The name "Frenzy" was later applied and is what it is currently as the trademark was available for the action figure.
Phazer