In response to JimfromFlorida's comment:
Obstruction (Rule 7.06) is called when the defense hinders the runner’s ability to run the bases. There are two different applications of the rule. One causes an immediate dead ball and the other is delayed dead. If a play is being made on a runner who is obstructed, the ball is immediately dead. If no play is being made the ball is delayed dead. A play, for purposes of this rule is when the ball is being thrown, or is in-flight, heading toward the base to which the runner is heading, an attempted tag, or when the runner is caught in a run-down. The rulebook definition is:
A fake tag is considered obstruction. A fake tag is when the fielder is at a base and takes an action that simulates an attempted tag, which causes the runner to slow down or slide. Faking a catch of a ball while not near a base or the basepath, is not a fake tag.
The fielder may stand in the basepath without the ball IF the throw is almost to him, and he needs to move there to catch the ball. This is considered “the act of fielding.” However, he may not actually block access to the base until he has possession of the ball, or starts the act of fielding. Until he has possession, or becomes “in the act of fielding” the ball, he must give the runner some way to get to the base.
It is never obstruction when the fielder is in the base path while he is attempting to field a batted ball. Obstruction only applies when the fielder is in the path for no reason, or is in the path prior to being in the act of fielding a throw, or does not have possession of the ball.
A fielder's "attempt to field" a batted ball ends immediately upon missing or deflecting the ball and such fielder must, in effect, disappear or risk obstruction.
A fielder is "in the act of fielding" and it is NOT obstruction, if, his block of the base, is a fluid, continuous result of his effort to glove the ball.
Separate, discontinuous movement, whose sole purpose is to block the base, is obstruction.
As with interference, obstruction is also a tough judgment call. Contact between the runner and fielder is not necessary to meet the definition. If a runner must slow down or alter his path to avoid a fielder who is not in possession of the ball or "in the act of fielding" a throw, he has been obstructed.
If no play is being made on the runner at the time he is obstructed, the play continues. “Time” is not called until all play ends. The tough part comes when the play stops. The umpire will award the runner the base to which the umpire believes he would have reached had he not been obstructed. The play ends and “Time” is called, when the obstructed runner is tagged out, or he ceases to continue to advance, or he gets caught in a run-down, or all action ends. At that time, the umpire may, award bases or not, in order to nullify the obstruction.
For example: the batter hits a ball in the gap for what looks like an easy double. No play is being made on him. As he rounds first the fielder is in his path and they collide. The batter stops at first. The umpire will award the runner second base, if he believes; the runner was making a legitimate effort to advance to second base and could have made it, had he not been obstructed. The umpire will protect the runner back to first base, if the runner was not making an attempt for second, but the obstruction hindered his ability to get back to first, before being put out.
It does not matter where the obstruction occurs. If a runner is obstructed at first base and the umpire believes he could have made it to third base, he will be awarded third. The umpire must be the judge. If, in the umpire's judgment, a runner is slowed down at first base, and the umpire judges that the runner had a chance for a triple, but then is thrown out at third base, the out should be nullified because of the obstruction at first. However, if the runner is obstructed at first base and the umpire believes that only a double is possible, and the runner advances to third and is thrown out; the out would stand.
If the runner reaches the base to which the umpire has protected him, and he advances further during the action, and is put out, the out will stand.
An immediate dead ball obstruction is called when obstruction occurs while a play is being made on the runner.
For example: a runner on first is attempting to reach third on a hit. A fielder obstructs him, between second and third, as the throw from the outfield is heading toward third. This is a play on the runner. The umpire should call "time" when the obstruction occurs and award the runner third base. Another example is a run-down play. It does not matter which way the runner is heading. If he is obstructed while being played upon in a run-down, he is awarded at least one base beyond the last base he held.
If a runner is obstructed attempting to get back to first on a pick-off play, the ball is dead and he is awarded second.
Here's MLB's obstruction rule:
OBSTRUCTION is the act of a fielder who, while not in possession of the ball and
not in the act of fielding the ball, impedes the progress of any runner.
Rule 2.00 (Obstruction) Comment: If a fielder is about to receive a thrown ball and if the ball
is in flight directly toward and near enough to the fielder so he must occupy his position to receive the
ball he may be considered “in the act of fielding a ball.” It is entirely up to the judgment of the umpire
as to whether a fielder is in the act of fielding a ball. After a fielder has made an attempt to field a ball
and missed, he can no longer be in the “act of fielding” the ball.
For example: an infielder dives at a
ground ball and the ball passes him and he continues to lie on the ground and delays the progress of
the runner, he very likely has obstructed the runner
by rule i could be(and was) called...FTR imo totally unintentional but still callable....tough way to lose