From Fallen London Wiki
<a href="/wiki/Perform_in_a_Mutton_Island_mystery_play" title="Perform in a Mutton Island mystery play">Perform in a Mutton Island mystery play</a> seems to have switched to scale off Persuasive instead of Watchful, but that answer wouldn't hold here, as my base Persuasive is 205.
e: But my base Dangerous is 200, so if it's been switched to that instead, that would explain it.
e2: a friend with 68 Dangerous/59 Shadowy is getting 2 tales per action, while my Shadowy is high enough that I'd be getting 8 if it was that, so I think we can conclude it's Dangerous this year.