This entry comes in response to this article about Geoff Jenkins' struggles this year.  I'll try to stick right to the point and let the pictures do most of the talking.

I do have to say Jenkins is one of those guys that is so much fun to watch.  Even if he never hit some of the monster bombs that he does hit, watching him take those serious rips is worth tuning in.  I love a good leg kick, and his is second to none - it's in the Juan Gonzalez category.

When a player has a "style" that is slightly different, it is easy to point the finger there right away when something starts going wrong.  Of course, I wanted to take a detailed look and see if the video showed any significant changes.

Here is a full shot:



The Clip
My video is limited but I thought the differences here were clear enough to use these clips.  On the left is a swing from 2004, 2005 in the middle and 2006 on the left.  The '04 and '06 are HR's (to right and center respectively) and the '05 is a single to left.  Obviously, they are not identical situations and results, but what I wanted to look at closely was the leg kick and what was happening before footplant.  Regardless of the result, each swing is initiated the same way, so if we're looking at setup and preparing to swing, we can make this work.  The '04 is also a little different angle, but the differences I see can be clearly seen even if the angle is slightly different.  Lastly, to keep my bases covered, the '05 shot in the middle is slightly different frame rate (or there are just missing frames) than the others, but the changes appear to happen later in the swing.

Ideally, you want video that matches closely like in the A-rod and Giles clips I did, so what I did with this one was extract frames where each clip is in a similar spot.  I used four:  the start, toe touch, footplant, and contact.  This way, regardless of frame rate or missing frames, we can control similar points in time to check out the swing.

So I'm really just posting the above clip so everyone can see the full clips together.  I synched it up to footplant.

Here are the four pictures, with some quick observations, which will be followed by more detailed explanation at the end.

Start



Upper body tilted forward much much more in '04 and better loading of the hips in '04 and '05 allowed easier, more efficient move forward.  Body was held together longer, enabling more powerful, efficient rotation.  All this adds up to getting the barrel to the ball quicker, easier and more consistently.

Also major difference in the back leg.  The leg gradually straightens out from '04 to '06 and the back foot goes from turned in to fairly straight (parrallel to line at rear of batter's box)

Toe Touch



You can see how his head position has gradually shifted from slightly left of center ('04) to center ('05) to slightly right of center ('06)

Footplant



Jenkins' head in '06 is now left behind his back knee.  You can see the differences in his head position relative to the back knee, which is result of the setup as shown in the previous pictures.

Contact



Have to note that contact in the '04 clip actually takes place in the next frame.  I used this because their bat is in same relative position.  The '04 he gets a little more in front and pulls to right field.  The '05 and '06 are going to opposite field.
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Thoughts and Observations

Changes in the back leg

1.  Back foot used to be turned in.  This typically helps load the hips more, making it easier to work off of the back leg to get the body moving forward.

2.  Gradual loss of flexed back leg.  Not necessarily a bad thing, but it seemed to coincide with keeping the body together (hips loaded longer, and maintain balance longer).
This may help with timing also since the hips will be lower to the ground with a more flexed back leg.  This way the leg has less distance to travel on the way down from the leg kick.  This can help stabilize head movement also.

'06 looks more like a reach with the lower body.  '04-'05 are better at moving the hips out from under the shoulders to create a shift into rotation.  '06 is leaving the upper body behind.

Tilt

If you start with your upper body titled forward, and then you move your hips out, you are in good position to launch your swing.  When your upper body is straight up and down at the beginning, and you still move your hips out the same way, you are left in a much weaker position.

Contrary to popular belief, you can start with your upper and still keep your weight back.  Jenkins is an awesomely extreme example of this in '04.  Upper body tilted forward, weight obviously against his back leg and his leg kick reaches the top.  Beautiful.

Adjustments - coming in from the cold

The very good news is that the adjustments should be relatively simple.  You don't need to change what your body is doing, just start it from a little different position.  Kind of similar to the Marcus Giles situation.

Quick Fix - some setup changes specific to Geoff Jenkins
1.  Turn the back foot in just a little like you used to
2.  A little more bend in the back leg to make a stronger base to work against

For what it is worth, I'd say don't be too quick to abandon the leg kick that has been so good to you.  Again, if timing is the problematic issue,, these adjustments will allow you to create a much more efficient shift forward with much less effort.  It really has less to do with how high your leg actually goes, but more to do with how you set yourself up and use your hips.

There is no reason to believe you can't regain your swing of old if you just go back to what you were doing then from a mechanical standpoint.

I personally would go for a mix of the '04-'05 swings.  Just get set up somewhere in between there and enjoy the mushroom cloud explosions off of your bat!
 
                                                           
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this is just a little additional thought as I continue to look at the video...

scroll back up and watch the full video and take note of Jenkins' front leg.  What I see is much more movement in his front leg on the right ('06) than ('04).  Why?

See how much more erect Jenkins is standing in '06?  Essentially the leg is just going up and down, whereas the leg kick in '04 does much more to help Jenkins load the hips, keeping himself together and preparing to unload.  By comparison, it seems like the '06 leg kick is much less efficient/effective. 

Just sitting a little more on/against that back leg puts the center of Jenkins' body a little closer to the ground and he doesn't quite have to do so much reaching with that front leg.  It also keeps the middle of his body loaded, so he can really be aggressive as he launches his swing.