I actually don't agree with your saying of "when power decreases, so does average". Ichiro for example. Ever watched him in batting practice? The guy bombs the ball consistently. Teammates say he could easily be a 30 HR hitter. However, Ichiro hits the ball to get on base and produce more runs that way. Also, take a look at Ryan Howard this year. April, .288 AVG, 4 HR. May, .250 AVG, 10 HR. To a much lesser extent, more example:
Gonzalez - April, .333 AVG, 9 HR.... May, .250 AVG, 11HR
Ibanez - April, .359 AVG, 7HR... May, .312 AVG, 10HR
Dunn - April, .310 AVG, 6HR... May, .243 AVG, 10HR
Bay - April, .324 AVG, 5 HR... May, .264 AVG, 10HR
Bruce - April, .258 AVG, 5HR... May, .212 AVG, 9HR
You get the idea... So Wright batting .320 to .330 seems like a safe bet for me, if he's hitting for the gap.