I truly enjoy ctf, however, it's easy to master the AI. Perhaps only a few have have yet to achieve 100% win rate against AI, but it will not take long before more players will figure it out. Its not that hard. There are many comps to easily achieve 100% win rate in ctf arena.
My solution is to change the scoring system by increasing the scoring gap. Final scoring should be based on the difference how much flags you captured versus your opponent. Capturing 2 flags without yielding any to your opponent will give u a maximum score with 2 flags versus 0 to your opponent. If you win by capturing just 1 flag and your enemy with 0, thats 1 flag point. Winning by capturing 2 flags and yielding 1 flag to enemy should also be scored as 1 flag point.
In my experience, I can already score 100% win, but its still a challenge for me to prevent the AI in scoring a single flag. I noticed the score i get from my wins regardless if enemy captured a flag or not is marginal. If you widen the scoring gap, the battle for scoring in ctf would now be how much flags you captured and how much you yielded to the enemy.
Or then again, if my idea is not feasible, perhaps you can just improve the AI once more.