If you guys saw the posts last week about team selection, you would see that Reidy isn't highly rated and the better option was Jackson leading the ruck with Treacy backing up like earlier in the season. That would be your answer.
In Reidy's absence on the weekend, Knobel had the opportunity to lead the ruck for Peel and put in a fantastic performance as a 20yo showing how you dominate as a ruck at WAFL level. He had 50 hitouts, 16 touches and kicked a beautiful goal. He dominated the ruck and contributed well around the ground, unlike Reidy who has only had more than single figure disposals 4 times in 11 games while kicking 1 goal for the year. The only downside was not having Ras and Brodie there to capitalise on his ruck dominance.
The coaches see Reidy every week at training and in the WAFL, there's a reason they aren't playing him as a lead ruckman. Knobel is actually closer to it than Reidy and he's in his second season. At 206cm, he still has some filling out to do but he looked very good on the weekend. Needs to work on his agility and ability to run up and down the ground but does well when around the ball.