Jay Bruce of the Cincinnati Reds began his time in the bigs as a power-hitting, pull-hitting phenom. Pitchers adapted and threw him plenty of off-speed pitches and fastballs to the outside corner and beyond of the strike zone. Bruce struggled to adjust, and his struggles continue today. He is a prototypical streak hitter who hits the ball well for a while, then cools considerably. He is in a constant mode of adjustment and re-adjustment, and it all centers around whether he is swinging well (hitting the ball, hard, the other way) or whether he is swinging poor (attempting to pull the outside pitch, resulting in weak grounders and plentiful pop-ups).
The struggles of Bruce, in regard to hitting the outside pitch, are mirrored by almost every batter. It’s a constant battle, in particular for a power hitter, to forgo an opportunity to pull the ball and instead take the pitch to the back side. Hitting to the opposite field must be a staple of your hitting drills regimen, if you want to move past being a streak hitter and become a great hitter.
From May 2011, http://raisingahitter.wordpress.com