Rule 2.00 ILLEGAL PITCH

ILLEGAL PITCH

An ILLEGAL PITCH is (1) a pitch delivered to the batter when the pitcher does not have his pivot foot in contact with the pitcher’s plate; (2) a quick return pitch. An illegal pitch when runners are on base is a balk.


DISCUSSION:
Illegal pitch when the pitcher's foot is not in contact with the rubber.Pitcher delivers while not in contact with the rubber
http://chicago.cubs.mlb.com/video/play.jsp?content_id=8406343&c_id=chc  

Spike caught in rubber, pitcher attempts throw, but delivers off the rubber
http://mlb.mlb.com/video/play.jsp?content_id=8633751

Illegal pitch when the pitcher pitches with the obvious intent to catch a batter off balance. This is also called a "quick return pitch" [Rule 2.00 QUICK RETURN] or a "quick pitch."
Pitcher delivers a quick pitch. No ball is assessed. This is incorrect. With no runners on base, a quick pitch is a ball. With runners on base, it is a balk. [Rule 8.01(d)]
http://mlb.mlb.com/video/play.jsp?content_id=17074027  

Pitcher is called for a quick pitch, however this does not appear to be a quick pitch as batter is ready. There is no requirement to stop during a stretch with no runners on base
http://mlb.mlb.com/video/play.jsp?content_id=18525879&topic_id=9780550&c_id=mlb

Not a quick pitch
http://mlb.mlb.com/video/play.jsp?content_id=18938433&topic_id=9780550&c_id=mlb