Do you know why you teach what you teach to your hitters? If I stopped you right now and asked you to tell me a couple advantages of any part of what you're teaching, could you do it? If not, it's time to kick into gear your learning habit and pick up some instructional strategies.
I've picked a couple parts of the baseball swing mechanics I hear taught repeatedly that are incorrect. Don't worry, I'll follow my own advise and explain why. Don't just take my word for it, however, ask around. Get other perspectives. But most of all, build your baseball swing knowledge base. Baseball instruction is a funny thing. You can find information and hitting "experts" everywhere. However, please for your own sake make sure that you are qualifying your sources of information first before you accept it. If you don't, you'll end up spending a lot of money, and changing your philosophy often.
Two Mechanical Fallacies:
1. Keeping your back elbow up is NECESSARY for a proper baseball swing.
I hear this advice mostly in Little League or in some of the younger age leagues. There is no physical advantage or benefit for a hitter to keep his back elbow up (often sometime much above the back shoulder). I'm not quite sure where the idea originated, but I do know it spreads like wildfire. It's like the cure all for a poor baseball swing. When it doubt, it must be the back elbow! And you can be sure you'll sometimes hear from the dugout or the stands, "Keep your back elbow up, Johnny!"
Keeping the back elbow up for younger hitters is often a source of a slow and long swing. When the bat head travels into the zone, the elbow of the top arm on the bat is down and relaxed close to the hitters body (if done correctly). Because of that, it makes little sense for a younger hitter to move his back elbow from a stiff position in the stance to a relax and collapsed position in mid-swing. Extra parts moving during a baseball swing mean less consistency. As a hitter gets older, his preference may be of a back elbow that is raised some. At this point (assuming he understands swing mechanics) he can make the adjustments as necessary.
2. Rolling your wrists as your bat comes through the zone is a must to create bat speed.
I have to bite my tongue (quite hard actually) when I ever hear this advice being offered for baseball instruction. While the back elbow up philosophy can be dismissed somewhat as a youth baseball strategy that does relatively minimal damage, this wrists rolling business can not be ignored in order to create a fundamentally sound baseball swing.
What "Wrist Rollers" can't do:
A. Hit an inside fastball to the pull side (right field as a lefty and left field as a righty).
B. Hit an outside fastball with any consistency to the opposite field (left field as a lefty and right field as a righty).
C. Hit line drives with back spin consistently (you know the kind that get over an outfielders head in a hurry for a double).
Here is why I can make those statements so confidently. In order to roll the wrists through a baseball swing, your arms must be straight at the elbows on contact with the baseball to do so. Youth hitters can get away with this because the velocity of the pitch is not overpowering yet. Add another 10-15 mph to the pitch and those inside pitches cannot be hit (or if they do, it stings) because the bat will be slow to sweep into the hitting zone. Outside pitches will also be difficult because the barrel of the bat will only cover the outer portion of the plate a fraction of the time necessary.
So what to do?
Teach your athletes when hitting a baseball to have their palm facing up on their top hand as they come in contact with the baseball. As the hands stay close to the body through the swing, the hitter will extend his arms after contact is made with the pitch. This proper extension is extremely important for good bat speed and plate coverage.