You have to be a subscriber to get at this, but Jason Collette does an excellent breakdown of Choo's revival at Rotowire this week. The link will take you there: http://www.rotowire.com/baseball/showArticle.htm?id=25368. But to read the whole thing you have to subscribe. 

Jason's point, in a nutshell (with plenty of graphs), is that Choo was hurt and struggled in 2014 and spring training in 2015, and then got overanxious early last year. His wife said something like, stop swinging so much, and he took her advice, and his second half was monster. 

Smart analysis and good news, I think.

I don't see why the current rule is a problem. Let them play!

The amazing thing is this has never happened before, that anyone can recall.

The fix is simple. Dead ball when this happens (batter intentionally or unintentionally gets in the way of the catcher's throw back to the pitcher). The catcher has enough duties!

There's great still photo of the throw at BP.

http://www.baseballprospectus.com/article.php?articleid=27687

I don't think "the bat was out of the box" is relevant under the language of the rule; the rule talks about the batter being in the box. And, I'm not so sure intent is so hard to glean. Choo was clearly not looking at Russell, was stretching his arm (adjusting his sleeve), there's no way he intended to interfere with the throw. I would also suggest that the catcher has a duty to be careful with his throws, even as it is true that this happens so rarely.

The argument at the time centered around: 1) if Choo's bat was out of the box when the throw hit it and 2) if Choo himself was out of the box. 

Based on that interpretation, I agree with Megary regarding the fact that the rule was correctly applied. But the rule stinks. It's next to impossible to prove intent unless it's blatant, and going forward I'd argue that anything more than incidental movement - intentional or no - and the ball should be ruled dead.

"Over the plate" is a slight overstatement, but his left hand, with the bat in it, is extended close enough to the the plate that Martin's normal throw back to the pitcher is obstructed.

Was it intentional?

No! Clearly not. But just as clearly he obstructs Martin's normal throw.

So that's the question: does unintentional obstruction make it a dead ball?

LVW is absolutely right; it would never have happened if Choo had been allowed to collect himself out of the batter's box.

Sadly for the Rangers, but fortunately for baseball, Elvis Andrus made all this moot.

The funny thing is it never would have happened if MLB hadn't added the staying in the batter's box rule. Choo would have been a couple of feet away without that rule.

Picture from Fangraphs of Choo's position in previous AB when Martin threw the ball back to the pitcher:

If Choo engineered Martin hitting the bat he did so making no overt movements. If he did engineer it, he laid a trap and waited patiently for something most of us couldn't even imagine ever happening, much less with a runner on third in a tied deciding playoff game. 

I'm with Megary on the position of the bat. Maybe above the inside line of the batters box. Not really close to the plate.

Every image I have seen shows clearly that his bat was definitely NOT over the plate.  The bat may have been out of the batter's box...maybe.

His intention for extending his arms is his own, but his reaction after Martin's throw tells me he never thought about possible interference.