I think there will be different approaches taken by clubs. Carlton are likely to use O'Hailpin because our best 21 have more speed than height. We can take advantage of our strengths by not committing a bench spot to a KPP, yet still have someone there for insurance. Running players are less likely to be subs for most teams as they can be used in high rotation areas. Teams will want a sub who they don't feel tactically pressured to get on the ground early. I can't see subs getting a run before late in the third quarter in injury free games. Any earlier and there's a big risk late injuries will further deplete the bench. On a side note, there is a chance this rule won't last the season. Injuries will increase again as players are pushed to go harder and faster. I'm even dubious as to how much it will affect interchange numbers. Teams will just rotate three guys more efficiently. The average number of interchanges might come down a little but with only 21 guys in the rotations it won't result in less running. There will be cries to dump the sub rule and I think they'll start early.
I'm thinking big Q lynch for the eagles. I don't think there will be a specific type of player used, I think it will always be based on the team selected to start. KPP's may be an effective way for coaches to re structure if a game starts to slip away. If there is a game where it looks likely to rain then they may start tall and have a small as the sub or vice versa.
I'd bank on the Sack at Collingwood. Not quite best 21 and can play forward or back. Jolly to rotate/rest with Leroy. Taz will probably start the year on field. Ball can't go for more than 8 minutes at a time I hear, so Blair will be needed to give him a chop outin the grunt stuff. Otherwise, I can see the rule being used to introduce a few of our rookies that would otherwise not get any game time. Run them hard for 60 minutes, then blood the next kid. If the club is serious about staying up for many years, then they will have to use strategies like this to avoid letting the list get too old and stagnant.