I think the truth of the matter is that the Royals were defeated by incorrect expectations on this play. Gordon hit the ball hoping it would be a single but fearing that it might get caught. He was running 3/4 speed to first. Buster Posey was strolling out to the mound to congratulate Bumgarner. Bumgarner certainly was not backing up second or third. So, obviously, when the ball was hit, the view at home plate as it seemed to everyone in that area was that the ball was the final out. Gordon was one of those folks.
The centerfielder, however, was playing too deep. He couldn't reach the ball, and he was frozen into neither diving for the ball nor just letting it fall for a single. Gordon could scarcely have believed that the ball would be so horribly misplayed.
Now, the ball WAS, in fact, horribly misplayed and Gordon takes off for second and probably third. If he understands or believes that the outfielder will fail to cleanly pick up the ball, he will have his head down and be looking to score. As you can see from the shot of the 3rd base coach holding him up, Gordon is already slowing up and looking over his shoulder. He didn't anticipate yet another misplay.
I was a baseball outfielder in high school, but most of my experience with the difference between triples and inside the park home runs comes from playing shortstop in softball 1990-2006. As the runner, I was involved in that play probably 20 times, and, as the shortstop, probably 100 times.
--If a guy jogs out of the box and then is surprised by the bad play - it is likely a double. He isn't going to turn it on and reach third unless someone falls down.
-- If the guy goes 3/4 out of the box and sees such a misplay, he is going to 3rd, and if we get a clean pick up and a clean relay we may have him at 3rd.
-- If the guy goes hard out of the box, or is super fast, or really thinks our team is sucky at fielding, he puts his head down about 2/3 of the way to third and he is going to try to score.
As the shortstop, you keep looking over your shoulder to see where the runner is and how he is running. The key is, is his head looking into the outfield or is his head down and trying for that last base? There are VERY few guys who are so fast that they can look out into the outfield and not slow down.
Then the sole remaining issue as a shortstop is the relay throw from the outfielder. Ideally you want that up by your left ear (every shortstop is a right handed thrower), thrown very hard, so that you are going to be able to catch and turn and throw all at once. Like an outfielder on a sac fly, you do NOT want to be stationary when you are catching the ball.
If you break down the pictures from the link, you can see that Gordon was obviously not running real hard out of the box, he was looking into the outfield going to third, and, by his own admission, is not very fast. As he approaches third, the coach already is asking him to stop (which is what Gordon wants to do anyway). The only way that Gordon scores is if his third base coach is wildly waving him in and Gordon has to put his head down and give it his best. So, we will never know - once the stop sign went up, Gordon was never going to try to score.
But, assuming that he would have been asked to score, WOULD ALEX GORDON HAVE SCORED? I say 60% yes. The outfielder's throw to the shortstop is very low, and it would not have permitted the shortstop to gain any momentum to throw the ball home. Gordon would have been about 80 feet away from home if he was being waved, since he would be running full out. That shortstop throw from the mid-outfield bending down and facing the wrong way is nearly impossible. When you gather and later turn, your throw will be about 85-90% of maximum velocity, and the throw is almost certain to tail off line one way or the other. There is no worse feeling than letting that ball go and seeing that it has nothing on it and the guy will score standing up.
The pictures show that there is a second (actually third) relay lined up about 80 feet from home plate. So, if the throw is obviously off line, and Gordon is chugging, there is a chance that guy cuts it off and still gets him at home. But that is an even more problematic play for the defense. If the throw is so obviously off line, then the cutoff man need to run to chase it 5-10 feet, then somehow turn and make an accurate throw for the tag play at home. It is a 15% play. Why do we honor Jeter's relay flip against Oakland? Cuz it was so nearly impossible to do. But if Giambi makes a good slide, he is safe anyway.
In my opinion, if Gordon sees the 3rd base coach waving him, the shortstop has a 25% chance of throwing Gordon out, and the last relay guy has a 15% chance of cutting the throw and relaying it for the out.
60% chance that Gordon scores.
Chance that a good Royals hitter gets a hit off Bumgarner? Based upon experience in 3 games? Maybe 15%? Sending Gordon was a better play by a factor of 4.