I recently saw an MLB highlight in which a pitcher threw his glove up
above his head to knock a line drive hit off its course.  The batter
was a awarded a triple as a result of this violation.  My question:
Does the same penalty (3 bases) apply in the outfield if an outfielder
knocks a potential home run ball down?  If so, why (besides just plain
good sportsmanship) don't outfielders use this strategy to prevent
home runs?

Hello robotboy-ga,

I believe I have found the information that you are looking for at the
Major League Baseball website.


Rule 7.05 States the following:

?Each runner including the batter runner may, without liability to be
put out, advance_ (a) To home base, scoring a run, if a fair ball goes
out of the playing field in flight and he touched all bases legally;
or if a fair ball which, in the umpire's judgment, would have gone out
of the playing field in flight, is deflected by the act of a fielder
in throwing his glove, cap, or any article of his apparel?



Reference:

MLB.com
Official Rules: 7.00 The Runner  
http://mlb.mlb.com/NASApp/mlb/mlb/official_info/official_rules/runner_7.jsp



So, if I am interpreting this correctly, if in the umpire?s judgment,
the ball would have gone out of the playing field in flight, which
would make it a home run, the play is treated as a home run.
Therefore, there is no incentive for outfielders to use this strategy
to prevent home runs.



If I have misunderstood your question and have not provided the
information that you are looking for, please let me know by using the
request for clarification feature, prior to rating the answer.

Googlenut



Search Strategy:

Searched using Google for ?major league baseball?
://www.google.com/search?hl=en&lr=&ie=ISO-8859-1&safe=off&q=%22major+league+baseball%22


This led me to the Major League Baseball Official Site
http://mlb.mlb.com


I then searched for ?rules?.  This led me to the MLB Official Rules page:
http://mlb.mlb.com/NASApp/mlb/mlb/official_info/official_rules/foreword.jsp


I then browsed through the rules until I found one that answered your question.

Awesome. Thanks.

as a professional umpire working in the minors right now and hopefully
some day in the bigs I can tell you that....

If a player touches a ball with his glove, hat etc. (anything detached
from his person) All runners are awarded 1) three bases on a batted
ball, 2) Two bases on a thrown ball, and 3) One base on a pitched
ball.

Also as was anwsered previously if in the umpires judgement a ball
would have gone over the fence in flight without the interference then
the home run is awarded to the batter.

It is important to note that there is NO penalty for throwing your
glove or hat, mask or any other equipment at the ball, it is only a
penalty if the detached or thrown equipment actually TOUCHES the ball.