...is that there really wasn't a good angle to see what happened. The two review angles they did show, they showed them after whatever had happened had happened and the WR was tripping and going to the ground. So they didn't really even see what happened, just the results of the contact.
At one point one of them said something like "unless something happened before that, that we didn't see..."
And that's exactly what happened. They didn't see the most egregious actions that actually led to the penalty.
Now that it's been a few days - wasn't that also the play that the defender intercepted the ball? I can see a ref letting it slide if the result is just an incomplete pass. But if the result changes possession, then they really have to call it, in my opinion.