Physics was one of my favorite subjects ("Physics is Phun!"). I believe the physics of Adam Dunn's swing are a huge contributor to his problems. The solutions are easy (see below) if Dunn were a kid or instructable, but since he is a veteran with many prior seasons of success, I don't know if Dunn's problems can be fixed. The Sox are not trying the solutions you'd use with a kid or a minor leaguer.
Dunn has possibly the longest swing in the major leagues, measuring the total distance traveled by the end of his bat from the start of his swing through the hitting zone (follow through doesn't matter because once the bat leaves the hitting zone nothing more can happen). He's very tall, has long arms, stands away from the plate (unlike Q), uses a long bat, holds it at the knob, and swings with full arm extension. He starts with the bat way back and swings in a huge on-plane arc.
Dunn's swing is properly termed a "long" swing. Some people mistakenly say Dunn's bat is slow, because it takes him so long to get his bat from the starting position through the hitting zone (and yes, this is indeed a huge problem for Dunn). However, "bat speed" refers to the speed of the bat as measured when it is in the hitting zone. Dunn's bat speed is plenty high when it is in the hitting zone, which is why he can hit 450 foot home runs if/when he actually makes contact.
Dunn also waggles the bat downward (below horizontal) at the start of the swing, a "signature" move that is nearly as bad as Rios's hands-held-low stance, because it means they have to get the bat out of this poor position when they start their swings, which also takes time. Dunn and Rios would say their signature moves are for their comfort and timing purposes, but I would say that moving out of those positions determines the start of their swing, so they've lengthened their swings.
A super long swing like Dunn's has only one benefit: when he connects solidly with the ball, the bat speed is great and the ball goes a long distance. It has multiple drawbacks, some obvious, some less so:
-- The most obvious drawback is the amount of time it takes to get Dunn's bat into the hitting zone. The longer this time, the earlier Dunn has to make the decision to swing at a pitch, and the earlier Dunn has to judge where the ball is going to be when the ball enters the hitting zone. The result: many more swings and misses, or swings and fouls, or swings and weirdly hit balls that spin wildly into the field of play - and far fewer balls that are hit solidly (one can argue that every time Dunn hits a ball solidly that it should go over the fence, so he's only hit 10 balls solidly so far this season).
-- This also creates a huge hole in Dunn's swing: he becomes very susceptible to pitchers with deceiving off-speed stuff, because Dunn has to decide very early to swing. Pitchers know this, and can easily set Dunn up, as CC Sabathia did three times last night, by striking Dunn out on outside sliders nearly in the dirt which Dunn missed by a foot because he had already decided to swing very early in the pitch.
-- Dunn's swing is also completely on-plane, which is good for generating bat speed but bad for adjusting to how the pitch is coming towards the plate - in fact he doesn't adjust at all. If the ball isn't where Dunn thought it was going to be when he started his swing, he has 0% chance of hitting it. Many, many other hitters are able to follow the ball to a certain degree and try to make contact - in fact this is exactly what good contact hitters do, sometimes by even throwing their bat at the ball if the hit-and-run is on - but they sacrifice bat speed to do this adjustment during the swing.
-- Dunn never varies his swing no matter what the count or the game situation. He doesn't shorten his swing with two strikes. He doesn't try to go to the opposite field when the shift is on. He swings one way, all the time, every time. The opposing pitcher and defense know this, and take advantage of it by putting on the shift and pitching to his weaknesses.
For connoisseurs of hitting, the contrast between Dunn and a good power/RBI hitter like Paulie is night and day. Dunn's swing is a simple-minded power swing that never varies. Paulie is a much smarter hitter with completely different mechanics and much better results. Paulie is often able to work the count into his favor by making better judgments on what pitches to swing at, which gets him into more hitter's fastball counts. If behind, Paulie adjusts his swing to try to go to the opposite field or take what the pitcher gives him. AJ also adjusts well to the count, the game situation and the pitch, and he able to get more hits because of his adjustments. Dunn neither adjusts for the count or the game situation (by changing the stance or swing he decides to use) or during the pitch (by changing the bat path during the swing to make better contact).
I coach kids, and the solutions to Dunn's problems are easy:
1. SHORTEN THE SWING. Get rid of the waggle. Try starting with the bat 1/4th of the way towards the plate from Dunn's current starting position and only move the bat forward, never backward. Stand closer to the plate and choke up, especially with two strikes. Don't swing for the fences. Watch the ball and move the bat to meet the ball as the ball comes towards the plate.
There's no way to turn Adam Dunn into Rod Carew, and these changes will decrease bat speed and power. Dunn doesn't need to do all of these, but he should try some of them to certain degrees. 320 foot home runs into the right field porch at Yankee Stadium count every bit as much as 450 foot ones and are actually better, since a shorter swing gives you a better chance of actually connecting and hitting the ball 320 feet instead of 450.
It's been four months, and if there have been any changes or adjustments to Dunn's swing, I haven't seen them.
2. REDUCE THE PRESSURE ON DUNN BY BATTING HIM LOWER IN THE LINEUP AND SITTING HIM AGAINST PITCHERS HE HAS TROUBLE WITH (i.e. lefties). When you're struggling, the added pressure of coming to the plate in key game situations with men on base and a skeptical crowd aggravates the hitter's struggles. No Little League, high school, college or even AAA manager would continue to bat Dunn in the cleanup position after four months of nearly constant struggles and no signs of improvement.
So why aren't the Sox doing any of this?
I think the Sox and Dunn are afraid to make any fundamental swing changes for fear of causing greater problems (which is hard to imagine) and for fear of losing Dunn's power. Instead the approach taken by Dunn and Greg Walker has been to try to tweak things (like balance) to try to get Dunn back to the ideal Adam Dunn simple-minded long power swing that worked in the past. It's been four months, and it hasn't worked yet. Every single pitcher in the AL knows Dunn is struggling, and they are taking advantage of it.
I think the Sox are also afraid of the hit to Dunn's psyche if Ozzie were to bat him lower in the lineup. Yes confidence is very important in hitting and a necessary component of even being able to stand in a batter's box while Justin Verlander throws 100 mph fastballs within a foot of your torso. But I think Dunn has proven that he doesn't react well to pressure (all his prior success has been on second-tier NL teams with zero expectations for winning), so I would move to reduce the pressure and give him the opportunity to start building up some confidence by having some minor successes.
I wish the Sox and Dunn would change something. Right now I fear we're doomed for another month of Dunn's struggles until Viciedo finally comes up when the rosters expand, and then Ozzie will finally sit Dunn a little bit.
If there's one thing I learned in physics class it is this: you can't violate the laws of physics.