Clearly we want some depth, that a pick 98th kid in the draft won't be able to provide. We've signed Weller as a rookie, so he's being paid the same as a kid.
It can only be about him being someone who is "ready to go" rather than a kid who is probably 2-3 years away from being a fringe player the level (doubtful we'd get a star at pick 98).
We've lost C Ellis, Miles, Lloyd, Conca and Stengle (Although highly doubtful he'd play any midfield minutes at AFL level). We're in Premiership mode. We need to make sure if we lose someone like Prestia, we don't go with a kid with a pencil build and 0 games experience. That's not to say Weller would ever replace Prestia, but he'd minimise the impact.