-I want to critique, analyze and test 5E. But I feel I can't, at least not properly. An RPG system is a composite of its parts into a whole. A system in not just combat. It is how character abilities, special situations, defenses, attacks all interact with each other. How combat works will change as new things are added, such as hp inflation or backgrounds that grant combat bonuses.
For a glaring example, WotC has stated that some of the numerical stats in the current playtest are influenced by "hidden" factors, such as one of the characters adding to weapon damage because they had a background feat that provided more damage. That "feat" and its effect is not listed on the character sheet, just the numerical effect. Looking at the sheet and the impact it has on combat (more damage) alters the analysis of the combat in the play-test. There is an assumption (and rightly so) that the base damage of a character falls within the parameters of the numbers in the playtest, when in fact those numbers are affected by components not part of the playtest (backgrounds and "feats" not listed). But because of these "hidden" factors, it skews the test.
I understand why WotC is running the play-test the way they are. They want to isolate components of the system for ease of analysis. However, I don't think this approach will work. To get a true and clearer picture of system mechanics it takes being able to look at the entire system.
-Jack's Toolbook had a recent article on the percentages in the Advantage/Disadvantage mechanic and asked whether the swing in numerical value depending on the target number (and desired goal) is a handicap to the mechanic. I wanted to comment on the topic but couldn't (not registered). So here are some of my thoughts on the topic...
I've seen the various mathematic breakdowns of Advantage/Disadvantage and I have a simple understanding on the concepts involved as you outlined above. However, for me the bottom line is that Advantage gives the player a bigger chance of success and Disadvantage gives a player a bigger chance of failure. What the actual numbers and percentages are, are not as important to me. The net effect (+ or -) are what matters.
The goal of the systemic use of Advantage/Disadvantage is met. Does the character have Advantage in the situation? Yes? Then the player has an advantage with the die roll...and vice versa.
Also, someone mentioned a baseline + or -3 (roughly) as an overall average. Over the course of a campaign, the percentages and numbers will even out to roughly that number so it all comes out in the wash. If taken over an extended time period, instead of just looking at it on a one-time, single-circumstance die roll, it works itself out.
I like the Advantage/Disadvantage mechanic because it is an easy to implement system that accomplishes its design goal.