Why would Frank be flat-footed while in melee? Crazy rule.
He's not. It's just (usually) the fastest way to figure out Frank's AC without all the special dodging parts (e.g., Dex bonus, Dodge bonus, etc.).
Again, the decision chain for the 3.0 rule and the 3.5 option rule is:
1. Did you hit your original target? If yes, then you hit him. If no, go to step 2.
2. Did the cover make a difference in you hitting your original target? If yes, then you hit the cover, and go to step 3. If no, the your shot was way the hell off and you miss everything.
3. Did the cover actually want to be providing cover to your target? If yes, then check whether your attack roll hit the cover's AC, and do damage if it does. If not, go to step 4.
4. Does your attack roll beat the cover's AC? If yes, you hit the cover; roll damage! If you missed, go to step 5.
5. Did you miss the cover, but by an amount equal to or less than its Dexterity and Dodge bonuses to AC (e.g., you would have hit the cover's FF AC, but you missed its current AC)? If yes, then the cover dodged out of the way and didn't actually provide cover to your original target, so you hit your original target after all; roll damage! If no, then you completely missed the cover, too.
The reason this was dropped (move into the optional section) in 3.5 is that it offers at best modicum of realism at the expense of being a gigantic pain in the butt to adjudicate in evern the simplest form (a
hooter firing at an [O]rc on the other side of his [W]arrior ally):
S . . . . W O
It gets ridiculous when you run into things like a hooter trying to hit an orc s[H]aman in the middle of a melee of [O]rcs and [W]arriors:
Code:
. . . . . . . . . .
S . . . . . . . . .
. . . . . O . W W .
. . . . . W . O O O
. . . . . . . W H .