expert level play or spew?

[yourface]

BB is bad, like 90/45 and aggro over 40 hands
SB is a TAG reg, seems pretty good

BB has 4SB left on the flop

Limit Holdem Ring game
Limit: $5/$10
5 players
Converter

Pre-flop: (5 players) yourface is CO with K[img]/images/graemlins/diamond.gif[/img] Q[img]/images/graemlins/heart.gif[/img]
UTG folds, <font color="#cc0000">yourface raises</font>, Button folds, <font color="#cc0000">SB 3-bets</font>, <font color="#cc0000">BB caps</font>, yourface calls, SB calls.

Flop: J[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/spade.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] (9SB, 3 players)
<font color="#cc0000">SB bets</font>, BB folds, <font color="#cc0000">yourface raises</font>,

my thinking was that if SB had a strong hand he would have c/r the flop. by betting it looks to me like he is trying to use the BBs aggro and stack off tendencies to protect a weak hand like AK AQ 77 that I can push him off of

thoughts?