Attack power is far to easy to manipulate. Empty your roster, load it with weak dragons, keep dragons that are just strong enough that is’ not apparent you’re sandbagging.
I would never use someone’s attack power as a gauge. Just as their defense rating is far less important than the actual layout (but not irrelevant either). Defense is also more difficult to manipulate on the fly without negatively impacting your defense when not in war.
Although, I suppose you could have a “long” base as bait of sorts, and then pull in and rearrange for the war. Seems like a too much work to me… But I’m sure some people do it.
Or sub out a few 55s with 35s until a war is declared. Just be quick, since sometimes you have only a few seconds. Or, better, always drop the “real” towers in 10 minutes before war would start.
I guess I’m saying, like statistics, these numbers can tell whatever story you want.