I'm not exactly sure what it had to drop. The way you even draw your range seems a bit random to me, too hindsight. Here is what I propose. If I use my yellow lines, you can maybe start to see a range forming if we use the highs and lows of the bars I've picked (and even that is subjective. But that one pin bar is very much a failed breakout (or breakdown in this case). Its only 2 bars later, on that first big red bar, what we see the rally is failing.Maybe that will better explain why it had to drop.
We can contrast this with the whole range of a day from the open. One big range, and we also have initially a FBO on the first thrust up after FOMC. We see price went back into the range, and even twice, before it continued higher. Now in the blue case, it didn't go back down to the low of the range, and in the yellow case, same thing, price only went back into the range but didn't hit the top of the range, or maybe it even did if you used the body and not the wick.
But I think my point still stands that there was no way to know which way it would break until it did. The first attempt to break down was met with lots of buying at 5100, so who is to say it will try again and be successful on the second try??
. Can't complaint with the second pin bar and rest of the action, I saw it as a lower low followed by lower high.
I'm gonna leave it at that.