Patryn of Elvenshae said:
All you've done is redefine high Dex into "not really high Dex."
This, however, is immaterial, because it doesn't address the fundamental problem: Bob had a better chance to catch the chandelier 3 months ago than he does now.
He's doing the exact same thing he did three months ago - real time, mind you, and probably more like two weeks ago game time, depending on how often you play - except, inexplicably, it's harder this time. Also, suddenly, there's a chance that the chandelier will come crashing down on top of him - causing an ad hoc save or die, no doubt.
First, that's only a problem if it's a problem for your game group. For many of the groups i've been in, that would be a non-issue--especially if it meant that both players got to have fun because their respective characters got to do cool stuff when the opportunity came up. It only might become a problem if Bob then *does* try to swing on the chandelier, and performs less well and doesn't get to do cool stuff. For some playstyles and/or -groups, everybody having fun is simply way more important than consistency, either mechanically, or within the game world.
But, back to the actual problem (as in, a group for which the above is a problem). If nobody remembers, then it is, once again, a non-issue--nobody knows that the rules have changed. Likewise, it would be no benefit for the rulings to be consistent, because no one would have sufficient data to realize that the rulings were consistent.
If somebody *does* remember (whether a player or the GM), then they say so, and it's fixed, right there, before the problem occurs:
Player 1: i want to swing on the chandelier and drop on the guard
GM: hmmm..., ok, how about a jump check to get there, a strength check to hold on, and i'll treat it as attacking with surprise if you manage it.
Player 2: when Player 3 tried it at the lord's manor, you said it was a tumble check, and then treat the attack like a charge because of the extra momentum
GM: yeah, but that was when you were leaping down at the chandelier from a balcony--Player 1 is trying to jump up to the chandelier from the stairs.
or
Player 1: i want to swing on the chandelier and drop on the guard
GM: hmmm..., ok, how about a jump check to get there, a strength check to hold on, and i'll treat it as attacking with surprise if you manage it.
Player 2: when Player 3 tried it at the lord's manor, you said it was a tumble check, and then treat the attack like a charge because of the extra momentum
GM: ok. sure, that makes sense--we'll do it that way again. So, instead, tumble check, +2 to attack but -2 to AC.
or
Player 1: i want to swing on the chandelier and drop on the guard
GM: hmmm..., ok, how about a jump check to get there, a strength check to hold on, and i'll treat it as attacking with surprise if you manage it.
Player 2: when Player 3 tried it at the lord's manor, you said it was a tumble check, and then treat the attack like a charge because of the extra momentum
GM: Does that seem fair to everyone? OK, we'll do it that way.
or
Player 1: i want to swing on the chandelier and drop on the guard
GM: hmmm..., ok, how about a jump check to get there, a strength check to hold on, and i'll treat it as attacking with surprise if you manage it.
Player 2: when Player 3 tried it at the lord's manor, you said it was a tumble check, and then treat the attack like a charge because of the extra momentum
GM: Does that seem fair to everyone?
Player 1: But i'm no good at tumbling! Plus, i'm wearing heavy armor. But i'm really strong--i should be able to jump the 5' to the chandelier, making up for my lack of dexterity with brute power.
GM: ok, that makes sense. So, we'll stick with the jump and strength checks.
or
Player 1: i want to swing on the chandelier and drop on the guard.
GM: I'm thinking jump check to get there, a strength check to hold on, and i'll treat it as attacking with surprise if you manage it--does anybody remember how we handled it at the lord's manor last month?
Player 2: when Player 3 tried it at the lord's manor, you said it was a tumble check, and then treat the attack like a charge because of the extra momentum
GM: Oh. Well, what exactly are you trying to do, Player 1? Where are you going to jump from?
Player 1: i was figuring the open staircase--that's only 10' from where i am now.
GM: Then let's stick with the jump and strength checks--you're trying to leap up to something, while Player 3 was trying to catch the chandelier after leaping off a balcony above it at teh lord's manor.
or
something else. The point is for everyone to have fun, and for there to be as much consistency as the group wants--no more, no less. Inconsistency is only a problem if the group decides it is (just as millions of movie goers every year decide to suspend disbelief and not care about inconsistencies in movies they're enjoying, while others can't enjoy movies with inconsistencies [n.b.: i happen to be one of the latter, generally]).