I think Josh Starling has done a good job so far. With little to no fanfare he has stepped into the front row and keeps giving his all every week. He's not a flashy player and no one will ever accuse him of being a DCE or Foz in waiting. The way he plays reminds me a bit of Martin Bella (just takes the ball up hard), but he has done some good things.....such as preventing a try against Newcastle by running down a winger and throwing him into touch.
But the player I think has stepped up the most is Jamie Buhrer. If not for Gifty coming back soon he's pretty much made the lock position his own. I actually think he's a better player now than when he got picked for Origin a few years ago and its no coincidence that its come with him putting on some muscle. He'll probably go back to the bench when both Choc and Gifty return, but if we can keep him at the club I think he'll be our starting lock come 2015.
I agree with HappilyManly, Peta Hiku's best position is FB. However, with Snake back there in the form he's been in lately, and with the Wolf's problems, wing is where he is even though its not his position, though he is showing signs that he is getting better on the flank. It also helps that he has someone as good as Killer playing inside him.