I have to disagree and agree, first, that Sanchez was ever much in foul territory.
So following the lead of @chpettit19 with the screen shot, I will add these.
1. Here is Sanchez's initial set up:
Kudos to Gordon for covering third base. Also, I love Gio's gesture here. We're not cuttin' this one!
2. Then, here is the point in time where Sanchez is most in the baseline, preparing to catch the throw but if you slow it down, he's kind of rocking back and forth, probably just natural motion, but notice his right foot:
Sanchez doesn't have the ball yet and Merrifield is not at the plate.
3. Then a moment later, here is Sanchez providing a lane; his left leg is in the air, and is by no means planted in front of home plate denying an avenue (the spirit of the rule). Notice the right foot again back well into fair territory:
And the call on the field:
Out, and not even a demonstrative call. So while yes it was a close play, it wasn't that close, if that makes sense. Not very logical but it makes sense in my head, anyway.
Sanchez did it probably just the way you coach it? not sure
What's really unfortunate is that there is a video angle from the third base dugout camera that looks like Sanchez is blocking the plate old school style and falling all over the runner in a big cloud of dust. I'm sure that angle had to have had an effect on the overturn.
Despite the crow hops and clutches, I also thought Beckham made a pretty awesome throw, as good as a throw you could hope for, in my opinion.
But mostly I just disagreed that Sanchez did anything wrong and I decided I wanted to do a bunch of screenshots.