Originally Posted by TheVulture
I thought the general rule of thumb is a runner has to at least be within reach of the bag on a slide, that way he can't slide completely away from the bag by some ten feet like the runner did here where he clearly can't reach the base. If I'm not mistaken the rules for home are different, so they'd be irrelevant in this case.
The approved ruling holds that a runner is supposed to be able to reach the base on a slide into a base in which he is already out if he adversely affects the fielder from making a play to another base, otherwise the runner can be called for interference, in which case the teammate who would have been put out in the umpire's judgment would be called out. If a fielder is blocking a base, with or without the ball, the runner can go around him. This is true at second base as well as home. A fielder can be called for obstruction for blocking a base without the ball, but this is another judgment call as the fielder may receive the ball as the runner gets to the base.
Running out of the baseline applies to a runner avoiding an attempted tag from a fielder, not running to the base to avoid an inevitable tag. I have seen runners going around second base to get into it when it is blocked. Running out of the baseline also can be called when a runner is hit by a thrown ball on his way to first if he is within the box that runs down the line from the base. I have heard that umpires have called out runners for running in fair territory up the line if umpires ruled they did so to interfere with the play and caused an error (a bogus call in my view -- if you want to argue the batter runner interfered with you, hit him with your throw), but I have never seen it without the ball hitting the runner. I have, however, seen the ball hit the runner in fair territory without being called out.
Running out of the baseline is all about umpire's judgment and can even depend on the umpire judging a runner's intent. It isn't as if there is a designated out of bounds area where an umpire has to call out a runner.