He may no longer be the Reverse-Flash in Earth-2, but Eobard Thawne could actually be Zoom and that is the reason why the storyline has not been introducing other characters that could actually point to the identity of the alter-ego of the speed demon.
In Season 1, viewers knew towards the early half of the “The Flash” that Harrison Wells or Eobard Thawne is the Reverse-Flash. In the current second season, the only possibility of the identity of the villain is Harrison Wells again.
But it was clear that Harrison, or Harry to the STAR Labs team, that he was also under duress to bring “The Flash” to Zoom or the speed demon will kill his daughter, which he has been holding hostage.
Thus, fan notions that Eobard Thawne is Zoom may be accurate. It can be recalled that back in Season 1, the Reverse-Flash is the more powerful speedster than The Flash. On the current second season, Zoom is more powerful again with the Scarlet Speedster.
However, these are mere fan speculation at this time and only with the Season 2 finale of “The Flash” will viewers finally know who Zoom is. It could be known earlier than the Season 2 finale but it would no longer come as a major surprise to viewers by then.