Hewett has always been one of the better defensive midfielders in the league and I don't see why he'd suddenly turn into a ball-winning accumulator capable of pushing a 100 average. Cripps, Cerra and Walsh are all going to take priority over him when it comes to clearances and he's too good of a tagger to not be given jobs throughout the year.
Because if all he wanted to be was a good defensive midfielder he'd have stayed at Sydney. It's not like he got a big contract at Carlton so he went there for one reason and that's for opportunities to play a bigger/better role (He's not Victorian either fwiw, this was a pure football move).
Similar to Lyons leaving Adelaide, Kennedy leaving Hawthorn, Lipinski, so on and so on.
Perhaps an even better example though is Steele and Miller, they both were also excellent defensive midfielders but I'm pretty sure their teams are pretty happy they developed beyond that role that any fit and disciplined player can do to a similar level.
Carlton have a need, Hewett has a desire, it's a good mix.
I think 100 is definitely within reach, he's been close for extended periods at Sydney in a lesser role.
I agree his hurt factor isn't big though, I think 110 is very unlikely, so realistically you're looking at a D5/6 type as his high end outcome, the simple reality is that during the year there will be a couple of guys available for similar prices that can be nabbed, so really you're taking the value in advance rather than at the end. For comparison you could have had Dawson for 440k at round 6/7 and got a 107 average from there, Daniel at 412k at round 7 netted a 99 average.
Definitely think he's got the potential to be a very good pick. He's their 4th best midfielder and their 2nd best inside midfielder and Cripps is not exactly very durable so there's a very real pathway to the #1 inside role with not a lot of competition from behind. He also does a lot of good SC things, very clean disposal and good tackler is a good foundation point. I'm certainly tempted by him, if his role is locked in again next week then that would only help the case.