Berserk + DefenderFollow

Right off the bat I'll tell you the following: These "results" are merely "eyeballed" and in no way reflect any actual testing.

It goes like this:
String is fighting a Sand Beetle in Eastern Altepa Desert. They all check EP Low def, low eva. String normally gets hit by these creatures for anywhere up to 28ish (rare) but generally in the mid to high teens (15-19) per hit.

String uses Berserk.
String uses Raging Axe.
String uses Defender.

The "tried and true" method of using Defender to "cancel out" the effects of Berserk, in order to later be able to use Berserk on a WS again (cancel Defender, use WS, cancel Berserk).

Love this method, however...

When I have both Berserk and Defender up, mobs seem to ignore the fact that my DEF is right back to normal and they start hitting me more commonly in the 30s, with crits as high as 86 (just a few minutes ago), when normally their maximum crit damage was in the mid 50s region.

Again, this is all eyeballed, but I feel like somethings going wrong here. I feel like there's some kind of "hidden penalty" for having berserk up at all, even if it is supposedly balanced out by defender.

...Son of a! Moderator? Move please?

Sorry WHMs, my bad, wrong forum :(