...and that's what I just did. I played 14 rounds (forgot to stop at 12), and I came out on top, but by a narrow margin this time. In the end, I had 19:5 kills, but I had more trouble to get to the first rank. So apparently there really is a change from 70-99 to 100, unless I just had an exceptionally good evening yesterday and a lousy day today...
Anyway, since I am no pro, I would still say that the bot is too easy. Judging from the ranks I used to occupy when playing online, I would say that with skill 100 bots I ought to be on some middle - lower rank in the end, if that's possible.
Just my personal opinion, though, and it's always difficult to find a balance between bots that behave halfways humanlike and bots that are just outrageously good, but very... well, "botty".