IMO, that statement is too rigid an adaptation of what potentially happens...

(From the Markman results):

j. “varying together”2

The next term is “varying together.” The plaintiffs contend that the term means “both increase or both decrease.” The defendants’ proposed construction is “increasing and decreasing by the same amount.” The dispute is whether this term is limited to “the same amount.” The defendants claim that the only way for the invention to work is to match the clock speed to the CPU’s processing speed capability. According to the defendants, if the frequency capability increased from 50 MHz to 100 MHZ but the clock rate only increased from 25 MHz to 150 MHZ, then the CPU would not be operable. In addition, the defendants argue that there are numerous statements in the prosecution history stating that the processing frequency should “track” or “vary correspondingly with” the clock rate. See Response to Office Action, April 11, 1996, at 6, 8; Response to Office Action, January 8, 1997, at 4.

There is no limitation in the intrinsic evidence requiring the variation between the frequency capability and the clock to match exactly. The Court construes the term to mean “increasing and decreasing proportionally.”Here's a reach - Perhaps the clocking change vs. load can be equated to the way the heart/lungs react to a heavy workload- there really isn't a fixed proportional value that is at play in the heartbeat speed ramping process, but more of one briefly accellerating before the other, the other briefly lagging, perhaps some instabilities between the two before coming to the two new speeds, perhaps a proportionally equivalent ratio to the "non-load" condition, perhaps not...

But then whats the definition of that concept?

Regardless, it seems to me that the defense can't argue the top level mechanics of the patent, but want to try to wordsmith (or more aptly, worm) the definition to a different reality, hence a jury would have trouble with it, causing doubt.

Regards