Check out the above GIF from SB Nation.

My initial thought told me that this was a blatant interference and that the home run should not have counted.

I even dug into the MLB rule book to make sure. The rule comes from section 3, article 16.

When there is spectator interference with any thrown or batted ball, the ball shall be dead at the moment of interference and the umpire shall impose such penalties as in his opinion will nullify the act of interference.
APPROVED RULING: If spectator interference clearly prevents a fielder from catching a fly ball, the umpire shall declare the batter out.

Pretty standard, right? That was interference?

However, in that same article, there was more clarification on the ruling. And this is what convinced me that the call was correctly made.

No interference shall be allowed when a fielder reaches over a fence, railing, rope or into a stand to catch a ball. He does so at his own risk. However, should a spectator reach out on the playing field side of such fence, railing or rope, and plainly prevent the fielder from catching the ball, then the batsman should be called out for the spectator’s interference.

So by that first part, Reddick reaching over the fence means that no interference had to be called.

The second part in question is whether or not the fan reached over. I look at the GIF above and the replays repeatedly. And even though it appears the arms are over the wall, contact with the ball occurs above and behind the wall. By that, it is not interference.

And there’s this:

I am not so sure he would have caught it too.

So even though I wish it was interference, according to the rules I just read, it isn’t. I don’t think I am reading this wrong. And the A’s shouldn’t have blown the lead, so there’s that.