The figure chosen to debut Core class in the Studio Series line was Bumblebee movie Shockwave - a truly baffling choice - which came out four years after the Bumblebee movie, and two years before the Voyager class toy. In some respects, it was also better articulated than the larger version. Some might say that alone made him worth the price - perhaps even better value-for-money than the Voyager - but his 'vehicle' mode was almost identical in structure to the TransFormers Prime version of Shockwave, which wasn't exactly inspiring. There had been no concept art for Shockwave's vehicle mode, theoretically giving the designers carte blanche to create something unique. The other figure in the first wave was Ravage which, arguably, should have been included with SS #83 Soundwave, so it's no surprise that Hasbro would later decide to create more minions for Soundwave, given they're now mining the archives for concept art.
Rumble is an obvious choice, considering his popularity and the frequency of his appearances in the G1 cartoon, and the fact that both he and Frenzy have come along in almost every recent toyline, including War For Cybertron, Studio Series '86 and Legacy, essentially all being Core class, or the closest equivalent in that line... These have all been rather lacklustre, though, so let's find out if the Core class Studio Series Concept Art Rumble breaks this pattern.