[Bug-gnubg] Strange FIBS ratings

[Albert Silver]

I analyzed two matches in the past few days where coincidentally I made
some huge blunders and where my error rate came out as 22+, thereby
classifying me as a Casual Player. The problem is that the FIBS ratings
given are VERY different, and seem a bit generous on top of it. I can't
copy the statistics to the clipboard anymore (hint! hint!) so I'll copy
it from the exported TXT:

Match 1:

Overall statistics

Error rate (total)              -2.769 (-29.273%)    -1.134 (-14.183%)

Error rate (per decision)       -51.28 ( -0.542%)    -20.25 ( -0.253%)

Equiv. Snowie error rate        -26.37               -10.80

Overall rating                  Awful!               Casual player

Actual result                    +50.00%              -50.00%

Luck adjusted result             -11.78%              +11.78%

Luck based FIBS rating diff.    -186.55

Error based abs. FIBS rating    1465.2               1704.0

Chequerplay errors rating loss   353.5                344.7

Cube errors rating loss          231.4                  1.3  

And now match 2:

Overall statistics

Error rate (total)              -2.953 ( -7.597%)    -4.152 (-14.214%)

Error rate (per decision)       -13.86 ( -0.036%)    -21.97 ( -0.075%)

Equiv. Snowie error rate         -8.39               -11.80

Overall rating                  Intermediate         Casual player

Actual result                    -50.00%              +50.00%

Luck adjusted result              +8.76%               -8.76%

Luck based FIBS rating diff.     +74.55

Error based abs. FIBS rating    1936.0               1866.3

Chequerplay errors rating loss    95.9                131.8

Cube errors rating loss           18.1                 51.9   

How can I be rated 1866 with the enormous error rate in match 2?? And
why is it so much better than the first match with a huge error rate as
well?   

                                                Albert