Sadly that is July results, I think February would be more illustrative and useful however I actually feel (A LITTLE) better now comparing the two sets of data.
What is important to note is that the goal here is to score 266. These sets of data merely show a birds eye view of ALL TAKERS for Illinois in February 2017 and July 2016. You have to remember and keep in mind general, traditional assumptions when viewing these statistics. While painting with broad brushes here (dont be offended if I am a little to the point here)...
Traditionally speaking, February is comprised of repeat takers and first time takers who did not take the traditional July exam, the reasons for this are many, but the usual reasons are because the first time takers were nontraditional students from night or part-time programs or who ended up extending their law school program. Due to this general understanding of the group the scores and pass rates are routinely lower in February. Further, there are fewer testers in February so swings in statistics can be more profound. Ultimately and broadly speaking, February takers are of "less quality" than July takers on a whole.
When comparing July 2016 to February 2017 one need only look at the 270 score and 260 score as evidence. Those who scored a 270 (barely passing) in July were at the 34th percentile, meanwhile those who achieved the same score in February were at the 54th percentile. THis logically makes sense if you follow the assumptions from above, that February testers are "generally" of lesser quality, A 270 in February looks far stronger now than it does in July - which makes 100% sense as your score would be compared to more traditional test takers.
July 2016: https://www.ilbaradmissions.org/july2016-percentile-equivalent-charts
February 2017: https://www.ilbaradmissions.org/feb-2017-percentile-equivalent-charts
Now, saying all of that, it does still appear that this will be a historically low pass rate for Illinois. From doing my own basic math a 266 (passing) will place you at the 48.4th percentile (as it is likely rounded down, just call it 48th percentile. Meaning that 52% of takers (total) passed. Historically there is a gap of 8 to 6 points separating the "first time takers" pass rate and the "total" pass rate, meaning A conservative guess is that those first time takers passed at approximately a 58% rate meaning repeat takers hovered somewhere around 48% passing (there are less repeat takers traditionally so I wont take a full 6 point swing DOWN). I am basing this on page 30 of this chart from NCBE: http://www.ncbex.org/pdfviewer/?file=%2Fdmsdocument%2F205
Do I think the new testing with 25 "practice" questions played a role in this lower pass rate? I do, but not in the way you may first think. I do personally believe that the NCBE knows what they are doing with the scaling of their test, but what may throw things off is this being the FIRST set with only 175 scoreable questions and then Illinois Reliance to adjust their scores to scale similarly to the MBE - so any quirks with the NCBE scaling will throw the IL essay scoring off a bit too. For those interested in reading a bit more about how (generally) the MBE is scored/scaled I reccoment the following piece that does a good job of explaining (in admittedly simplified ways) how each different MBE is scored so that each test is "weighted" the same and there is no such thing as one MBE being "harder" than another: http://excessofdemocracy.com/blog/2015/9/no-the-mbe-was-not-harder-than-usual
This all being said. Take a deep breath, less than 24 hours until you actually know something definititive. I wish everyone luck, I mean absolutely nothing negative about anyone who took the February bar (of which I am one) and I am anxiously waiting with all of you.