I disagree, most players don't perform from game one, a recent example being Andrew Brayshaw, averaging less than 12 disposals after his first 3 games as an 18 year old. The reason he is now able to get 25+ is because he was backed in, and has been in the AFL system and allowed to develop against players at AFL standard.
Looking at the bigger picture, Freo has an atrocious record of developing key forwards, and recently have tried buying one in without much success. Tabs is getting older, in 3 years he'll be in his 30s, if and when he gets injured, if the replacement choices are "some guy from Peel who isn't quite ready" or someone with 50 games under his belt, then I know who I would be looking at.
I'm not really getting the argument for not having him in the side? Then again, maybe you just like seeing Tabs getting double teamed every week.
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