It's my biggest gripe with the system so far too. It's silly that a level 20 Wizard is an even match with a level 15 Fighter for arm wrestling (or mighty close - the stat difference actually closes with leveling since you get 4 stats boosted every 5 levels). And AC increasing by level makes the range of balanced enemies very small compared to what you can throw at a party in 5th. Combined with full Hitpoint gain each level and you can outlevel things quickly.
I would rather see level drop to lvl/2 or so and increase the gap in the proficiency tiers (maybe -3/0/+1/+3/+5).
