The -4 penalty to an unskilled roll is intended to reflect the fact that hard work beats talent when talent doesn't work hard. In a two-man infantry buddy team, the guy with talent (Coordination +1 or +2) hits his targets 10-20% more often than his Joe Average partner – but either one of them is much more deadly and efficient with a rifle than an Olympian (Coordination +3) who's never fired one before.
That said, on this roll the results don't seem right. I'm not sure whether every adult should pick up a level in the Persuasion skill, or if Persuasion skill rolls should be contests between the characters so that negotiations between untrained people come down to a contest of personalities (i.e. a mix of psych profile and primary & secondary attributes). I'll give this some thought, any input is welcome (as always).
I think you get what I am talking about. Let's take the case (that maybe occurs in every game, because I think it has occurred in all of my playthroughs) of the MC trying to convince the prof to change a grade. It's a difficult case to make, so rightly requires a "10" after modification.
In all three cases below, the MC is assumed to have a +1 from all her attributes, and another +1 from dressing up.
With a persuasion skill of 2, the MC has a +2 (skill) and +2 (all other factors) for a +4 and thus a 50% chance of success (6 or higher on 1D10).
With a persuasion skill of 1, the MC has a +1 (skill) and +2 (all other factors) for a +3 and thus a 40% chance of success (7 or higher on 1D10).
With a persuasion skill of 0, the MC has a -4 (skill) and +2 (all other factors) for a -2 and thus a 10% chance of success (10 on 1D10 always succeeds).
This means that any player trying to maximize their chances will always seek the path that gives them the +1 in the most skills, even though that's not how we really live our lives. Going from 0 to 1 in any skill at all, regardless of profession, is overwhelmingly more important than going from 1 to 2 in any skill related to a profession.
This problem would not arise if skills just added their level to the die roll and a skill level zero was just one that added nothing. The problem with "dueling skills," while I like the idea a lot, is that you'd have to establish skills for the target all the time. I'm content with the RNG telling me that the prof was skilled enough to detect the MC's line of bullshit; it doesn't matter to the story whether the MC failed because the prof had a good bullshit detector, or was gay and thus not swayed by the sexy dress, or was just tired of coeds trying to weasel a better grade. If you want to randomize the reason for failure in the outcome report for "flavor" purposes, that would work and would be a lot easier than establishing skill levels for every RNG target.