I think Walker is a big game player. Has had some great moments against the likes of the Storm, Rooster, Rabbitohs over the years. He adds another dimension to our attack when on and generally widens it - acting as a mid-field link man that sends quick wide passes side to side. This faster movement side to side (vs Jake) could prove key to breaking up the defence of teams like the Storm and Panthers, giving time and space for Olakautau, Trbo, Saab and the likes.
He's still a work in progress but his defence (bar that tigers game, who play quite unpredictably and our forwards were slacking off in D) has been good enough I reckon, especially on the try line. Kicking isn't good but he could be used for short grubbers and is generally one of our better kick chasers.
I think we have to persist with him, it has the potential to break up the better teams in big games, even if just off the bench for a short period.