NLHE $0.5/$1 blinds, $70 effective stacks.

Kinda TAggy player who tries to play well opens from MP for $4.
Fnord calls from the button.
Blinds fold.

$8ish in the pot

Flop is:


TAggy bets $6, Fnord raises to $18.

TAggy is playing for stacks, Fnord is not. Discuss.