The $64,000 dollar question!
I have been very encouraged by Ainley's cameo performances when on for 15 minutes or so, but would like to see him start more often. Kirk has more to prove, I think - as you say gazan, never got going. I haven't seen Lowery or Dale so can't comment. Saunders has surely had his chance and Udoh will need to shape up. I just think of Colclough at a similar age to Ainley and he was more of a flash in the pan at that time, but his last 6 months with us was excellent, so I'm optimistic.
I have also been impressed with Wintle, who looks more of a man than the other lads mentioned; as you suggest, gazan, some of the others still look like kids - big season for those we retain, and I think Saunders will be the only one we don't.