We have all been there. Each and every one of us has spent days, months or even years speculating over a particular question posed by any movie or a show. But it is only after the speculation ends and the question is answered do we realize that the answer had been in front of us all along. The same is the case for The Flash.
The Flash had managed to keep the true identity of this season's big bad, Zoom, under the wraps for a much longer period than the previous season, where they went on to reveal Reverse Flash's identity as early as the midseason finale. However, The Flash writers learnt from their previous mistakes and rectified it. Unlike Reverse Flash's mask, Zoom's mask covered his entire face. Hence, the fans of the show had a hard time guessing which Earth-2 character was under Zoom's mask. The show left the fans speculating for months until they finally decided to reveal, in the 15th episode, the true identity of Zoom — Hunter Zolomon. But if you rewatch the second season of The Flash, you will realise that the answer was right in front of you all along.
Evidence of Teddy Sears' Character (Hunter Zolomon or Pretend Jay Garrick) Being Zoom from Early Season 2
Long before unmasking Zoom, the show gave us a hint towards Zoom's identity. You didn't need to be Sherlock Holmes to figure who Zoom was. All you had to do was to get some popcorn and watch the fifth and sixth episodes of The Flash again, carefully and back-to-back.
In the sixth episode of The Flash, Earth-1 Linda Park pretended to be her Earth-2 counterpart, Dr. Light to help Team Flash fool Zoom and defeat him. In that particular episode, the only people who knew that it was Earth-1 Linda pretending to be Dr. Light were Barry, Cisco, Caitlin, Iris, Joe and Harry. If only these people knew the truth, why didn't Zoom show up when Dr. Light called out Zoom and threw Flash's emblem through the breach?
None of the above mentioned characters had to tell Zoom anything. Zoom already knew the plan. Team Flash executed the plan in the sixth episode. However, they came up with the plan at the very end of the fifth episode. Joe asks Barry what he plans to do next and Barry in Jay Garrick's presence says:
"We do what Dr. Wells says. We use her to lure Zoom here."
And after having an argument with Dr. Wells and Barry, Jay left and wasn't a part of the next episode. He had no idea that it was Earth-1 Linda who threw the emblem. But he knew that they were going to use Dr. Light against him. As a result, he didn't fall for the trap. The Flash writers wrote both the episodes very cleverly. They made sure that Jay knew the plan, so that Zoom won't fall for the trap and they also made sure that Jay didn't play a part when they were executing the plan, so that no one would suspect that Jay is Zoom.
The writers of The Flash kept us waiting for a long time for the big reveal. But they did give us a hint. We just couldn't catch on to it. A lot of people had suspected that Jay Garrick is Zoom. But none of them had brought this up to justify their claim.