Well, with being out of town last week, and catching up from being out of town this week, I haven't had a lot of time for writing. I have played a couple of games since then, though, and I've had some thoughts.
Last week I ran the first part of the Dungeon Magazine adventure Lord of the White Field. From my read of the adventure, it looked like a few of the toughest encounters were loaded into the front of the mod. The party was faced with a level+2 and a level+3 encounter, each with secondary objectives, and they seemed to just waltz through them. I'm not sure what the player perception of the difficulty was, but it seemed to me that the monsters just weren't hitting often enough, even on the 'soft' characters, and this is using the new MM3 monster math. It just didn't feel right.
Looking at the math when I got home, the encounters were built so that the individual monsters were of party level or party level+1. The threat (on paper) was from the quantity of monsters. But for whatever reason, the party was built with defense in mind. The lowest AC in the group was 22 (for a melee ranger with no magic armor even! He should have been down in every fight!), so on the softest character the average monster had a hit range of 11-20 or 45%. Meanwhile, the PCs have a hit range of roughly 8-20, which means the baddies are sitting ducks.
The encounters so far have been designed with the monsters to come in waves. This has absolutely reinforced the 'zombie apocalypse' vibe that the mod is going for, but it means that the threat is spread out over the encounter. Unless the party has an unlucky round, the monsters don't have enough time to group up, position themselves and wear down the PCs.
When I first got home after running this game, I started brainstorming ideas on how to beef up the adventure to make it more of a threat. I could level up the monsters, or add some situational bonus that would let them hit more frequently. I could up their damage, so that when they do hit they have more of an impact. But then I looked at it from the player perspective: people usually build their characters to be good at doing things they think are fun. If someone chooses items, powers and feats that improve their thievery and stealth skills, they probably want to sneak around and open locks.
This party chose to design hard-to-hit characters. If I made adjustments to the mod to bring the hit range of the monsters more in line with my expectations, that would effectively negate the choices those players made when they created their characters. As frustrating as it seems to me to be unable to hit the PCs, they should be rewarded for choosing defensive options for their characters. In the long run, it probably means that they are each dealing slightly less damage per hit, and are healing slightly fewer hit points per surge, or their skill bonuses aren't as high as they could be.
I'll have to find a way to challenge them by making them feel those sacrifices: let them be hard to hit, but emphasize their weaknesses in other areas.