Omnifarious Grey
First Post
I don't think so - Bigbys does 17 on round 1, 12 on round 2 (in addition to an extra attack), moves and grabs another target on round 3 for another 17 (or keeps squeezing the first target for another 12)
By round 3 it is already ahead, and it could last for 9-15 rounds!
Additionally, I think that people often overestimate the benefit of doing a little damage to a lot of targets. They multiply up 6 damage by five targets and say "hey, that's 30 damage, that's pretty good".
This comparison for damage only is for when the fireball misses. If you actually hit and end up averaging something like 12 damage (roughly) then spread that damage out to those "5" targets, you get the theoretical 12*5=60 damage. this is slightly better than the (17+12)x2=58 damage that comes over 4 turns and requires two attack roles to get and assumes they don't escape.
I don't want to get into a discussion of comparing the powers (always a big fan of Bigby's in general). I would still say that increasing daily powers such as Fireball is something you can't just lightly try to accomplish.
Most of us have a beef with some things that Wizards has done, but "in general" they "tried" to balance as many things as possible; therefore I don't think we can give some quick assumptions to "balance" powers unless we go into big details with them.
I suggest taking a look at keterys' thread about Daily powers where he has some rating schemes drawn up. From here figuring out which powers work and which don't might give a better look into what needs to be tweaked if anything as well as a base for tweaking power by power basis rather than general statements.
There are my four cents worth.