Hmmm. I wouldn't be so quick to dismiss Carlisle if he's willing to come to us.
Do you ever wonder why we have to resort to Westhoff pushing back when we are already playing the likes of Carlile, Hombsch, Trengove, Pittard, Broadbent, Jonas/O'Shea and Impey/Krakouer? We already play a +1 in defense to begin with, so the mere fact that we still have to drop another player back should tell you how concerning our defensive structure is. But if we got Carlisle, we could free up Carlile to push forward as he sometimes does while not sacrificing defensive capability.
The defensive setup I see us playing is something akin to this:
Hombsch - Carlisle - Impey
---------Trengove--------
Broadbent - Carlile - Pittard
Swap out Carlile for Clurey when Alipate retires, and you've got a premiership defense right there for the next ten years. With Krakouer/Jonas on the bench to provide cover to both the defense and midfield. This also allows both Broadbent and Pittard to push forward as wingbacks when switching the play, safe in the knowledge that the weak side is covered:
Hombsch - Carlisle - Impey
Trengove - Carlile - Pittard
Broadbent
This also limits the ability of opposition to hurt us quickly on a turnover as the player caught out of position is covered by talls in the backline, meaning they can't just bomb it quickly forward. It's basically like having Westhoff back all the time.
Of course, there's no way I'd give up a top ten draft pick for such a luxury unless we really are going down the catenaccio 'attack from defense' style of playing and are going to ask guys like Broadbent and Pittard to basically act as defensive midfielders instead of the pure defenders they are now.