First, thanks for all of the constructive replies. I am a little surprised that no one else sees this as off since I often see low defenses mentioned as a balancing factor in other barbarian threads on this forum. I don't feel that very much offensive power had to be sacrificed in order to obtain high defenses on the class. His defenses are certainly not impossible to hit but they hold up well compared to the rest of the party. Here are the defenses for the party (AC/Fort/Ref/Will):
Barbarian: 29/28/28/23 (usually 31/28/29/23)
Starlock: 25/27/27/25 (+2 with shadow walk)
Inspiring Warlord: 28/27/25/26
Shielding Swordmage: 31/24/27/23
Laser Cleric: 26/22/22/26
I've included +3 armor, a +3 neck item, and the Paragon Defenses feat if the characters did not have them already. Will attacks seem to be the least common in the Dungeon adventures I have run (currently the Madness series of adventures from Dungeon magazine issues 161-163) so that helps the barbarian and swordmage out.
Looking at the numbers I think I can probably attribute the player discontent to the following:
- Some builds such as the laser cleric have a really hard time maintaining credible defenses.
- The barbarian has two reaction encounters (one from an item), a free attack on criticals, and a free charge on a kill. Between those and all the attacks the warlord grants him he ends up with a lot more 'screen time' in combat than any of the other party members. That also means more d20's rolled and more chances for massive critical damage.
- Rarity of attacks against will in many adventures masks the barbarian's low will defense.
I can adjust the attack types in the encounters and try to give the cleric some extra help but I'm not sure what to do about the screen time issue. I also still can't shake the nagging feeling that the party would be a lot more effective in most cases if it was composed of one or two leaders and all the rest as barbarians
PS: The barbarian is fine out of combat and I agree that it is not a balancing factor.