This is the pop-up news window in Beta today. It would appear from this that the decrease in SK from quests, quest milestones and log-in is a glitch, not a deliberate downgrading as has been suggested elsewhere.
This announcement originally appeared in Beta Forum's Changes to Tournaments thread, not the SK thread, with the explanation that somehow the game's re-programming for tournaments had caused this. That is not at all impossible; although I am not a programmer, I discussed this with one of the developers in Hamburg a while back. Different game modules sometimes use lines of programming code from elsewhere in the game - or even borrowed from other games! Game changes are most often made by patching new lines of code into the existing game version. This is by far the cheapest solution, because it requires a lot less programmers' time - though ideally it would be better to rewrite blocks of code rather than patch it.
As it was explained to me, when you patch code, you often come up against The Law of Unexpected Outcomes - another game module that uses some of that code suddenly goes dysfunctional - and that is the reason for quite a few of the game glitches that we see. The more patched a game becomes with time, the more likely something will go wrong.
This could explain how a glitch like this might come to be.
It will be interesting to see if the SK values in the Live version are the same as the ones we recorded in Beta.