Depending upon your partisanship, you have by now likely given thanks for, gnashed teeth over, or surveyed in mute wonder the fan-interference call that helped decide Game 4 of the ALCS between the Boston Red Sox and Houston Astros. The jumbled particulars of this pivotal moment mean that a tidy summary may be in order. What follows -- in pleasing and browser-friendly FAQ format -- is just such an endeavor. Let us begin.

What happened?

In the bottom of the first and with George Springer on first base with one out, Houston's Jose Altuve drove a ball to the wall in right field. Out in right, Boston's Mookie Betts -- perhaps the best defensive corner outfielder in the game today -- timed it up on the warning track and leaped for the catch. To the naked eye, Betts looked to be set to haul the ball in right over the top of the wall. At the same time, a tangle of hands from several fans reached out for the ball, and one fan almost certainly inadvertently bumped into Betts' open glove and closed said glove right as the ball was set to reach it. Crew chief Joe West ruled fan interference, which means Altuve was the second out of the inning, and Springer returned to first base. West's call was upheld after a 3-minute, 13-second replay review. 

TL;DR. Is there a video of the play I can watch?

But of course.

So what's the official rule in question?

Here's this from MLB Rule 3.16 (emphasis mine, but you can borrow it).

In every case of spectator interference with a batted or thrown ball, the ball shall be declared dead and the baserunners can be placed where the umpire determines they would have been without the interference. When a spectator clearly prevents a fielder from catching a fly ball by reaching onto the field of play, the batter shall be ruled out. But no interference is called if a spectator comes in contact with a batted or thrown ball without reaching onto the field of play -- even if a fielder might have caught the ball had the spectator not been there. 

Also, the interference must occur in front of the front plane of the wall and not, say, while the fan's hand is hovering over the top of the wall. So the question is whether the fan(s) who bumped Betts' glove, thus making a catch impossible, did so by reaching over the yellow line on the fence and into the field of play. Time for the grainy screengrab 

betts-interference1.png
MLB.com

This isn't definitive, thanks to the angle, which means we're in Rorschach territory. That means your interpretation of what you see above is probably going to track to your rooting interests. To these eyes, it does look like Betts' glove and the fan's hand making contact with it are on the business side of the yellow line (the white blur between Betts' glove and the fan's palm is the ball). Again, though, the angle doesn't allow firm judgments. 

Did crew Joe West explain his reasons for making the interference call?

Yes. Via Pete Abraham on Twitter, here's what West said of his on-field call: 

Q. What did you see that prompted the initial call of fan interference?
JOE WEST: Well, when he jumped up to reach for the ball, the spectator reached out of the stands and hit him over the playing field and closed his glove.

Q. So the ball had not yet crossed the railing?
JOE WEST: No.

Q. And Betts' glove had not yet crossed the railing, do you believe?
JOE WEST: No.

Q. OK. Did the fan -
JOE WEST: Here's the whole play, here's the whole play. He hit the ball to right field. He jumped up to try to make a catch. The fan interfered with him over the playing field. That's why I called spectator interference.

Q. So it's a clear call in your mind?
JOE WEST: Yes.

Q. Were there already - was there a single call that you saw, that the replay officials saw on replay that confirmed -
JOE WEST: I don't know what he saw. He just - the replay official said I was right.

Q. OK.
JOE WEST: That's all. He said I have nothing that can change it.

So in West's words, he perceived the contact with Betts' glove as taking place over the field of play. Thus, he ruled fan interference in accordance with the rule cited above. 

So the replay review found that West's call was correct?

That's what West says above, but that's not entirely true. The replay review came back as call "stands," which in plainspeak means there wasn't enough video evidence to confirm the call or overturn it. Stated another way, if West had called home run on the play instead of interference, that likewise would've stood. Again, there simply wasn't an angle that provided definitive evidence.

So why wasn't there a better camera angle on the play?

Well, it goes a little something like this: 

That also would not have been a perfect angle -- perfect would've been a camera positioned straight down the fence line -- but it would've been better than what we have. Unfortunately, the Minute Maid Park security worker was (understandably enough) craning to get a better view of the play. 

So did this wind up mattering in the final outcome of Game 4?

Quite possibly. The Red Sox prevailed by a score of 8-6 following a taut bottom of the ninth. In that first inning, Marwin Gonzalez reached via HBP following the Altuve call, and then Yuli Gurriel flied out to Betts to end the inning. If Altuve's drive had been ruled a home run, then you can argue that we're talking about a tie game after the Astros pushed across a run in the eighth off Craig Kimbrel. On the other hand, specific events in a baseball game cascade into other specific events, and an Altuve home run in the first may have changed tactical decisions both small and large over the remainder of the game. Still, the larger reality is that the Astros lost by two and Altuve may have been deprived of a two-run home run in an inning in which the Astros failed to score after Altuve was called out. 

As for the matter of it being a home run, well, it's complicated. An umpire's job when ruling interference is to, in the words of Rule 6.01(e), "nullify the act of interference." If, in the umpire's judgement, a ball is headed out of the park when the fan touches it, then he can rule it a home run. Since this interference call was precipitated by a fan's touching and closing Betts' glove just as the ball arrived, West "nullified" the act by calling Altuve out. Had a fan reached out and caught the ball as opposed to hitting the glove, then a different set of considerations would've been in play (although this might not have changed West's ruling). Alternatively, if the ball merely hit Betts' glove without any interference and then bounded back onto the field, then we're talking about a live ball. 

What did Kate Upton think?

With the caveat that she's a fan of her husband Justin Verlander's team, here you go:

Duly noted. Again, though, this all comes down to whether you think the fan in question reached beyond the front plane of the outfield wall, and we don't have indisputable proof of that one way or another. 

Any other famous fan interference calls/non-calls?

Sure. You've no doubt heard the name of Steve Bartman invoked since Wednesday night, and we all know that tale. There's also Jeffrey Maier, who famously assisted a Derek Jeter home run in the 1996 ALCS. Then there was another Yankees rooter, Jared Macchirole, who may or may not have made contact with Nelson Cruz's glove on a Robinson Cano drive to the wall in the 2010 ALCS. That particular incident spawned one of the great and most multitudinous GIFs in the vast sprawl of human history: 

Also, let's not forget Victor Martinez's disputed home run against the Athletics in the 2013 ALDS:

The finest of these, though, is found at the intersection of fan interference and heavyweight-championship parenting decisions. Come with us, won't you, back to Wrigley Field in the year of our lord 2015:

Anyhow, now get back to yelling about Joe West.