He also exaggerated and mishandled a few things but I have my doubts his announcement right before the election had the impact people like to assume it did. If you sat and listened to all the BS against Hillary and we're still for her at that point, his little announcement wasn't going to sway your vote. >.>
I assume this your opinion reflecting what you saw around in your personal bubble I.e reactions you saw personally around you, on your social media feeds and forums you frequent.
However, I saw from my bubble a lot of enthusiasm get deflated. I saw on my feeds plenty of ardent Clinton supporters have doubts on Oct. 28th and expressed they may not vote now. That went on for a week. The announcement that there was nothing came on Sunday the 6th. That's a weak day in the news cycle. The damage was done.
That's not saying it's the reason she lost in the electoral or the three key states. However it did have an impact due to the timing.
Speaking of timing, it is also the reason why people are looking at Comey's firing suspiciously.