shit, bot cant even beat me and i've given up trying to get X CC author to make it work..
A good CC can anticipate a little bit, but the bots can't read ahead unless they have more info to access.
a crazy amount of info.
A player can see options and use macros to 'push' commands faster through the client, but they can also anticipate and choose various options that the bot doesn't know about. certain procs, certain 'high damage' phases in a fight when you need to burst, i.e. vulnerable mobs due to a boss mechanic, or stunned characters.
if a custom combat class isn't hitting the same abilities as you, you'd really have to help show what it is you do differently, i.e. submit a combat log through a parser like WoL, WcL or AMR, compare that to a log of the CC's rotation. i.e. upload it to somewhere like
Warcraft Logs - Combat Analysis for Warcraft and sort by damage done / per user , like this
Warcraft Logs - Combat Analysis for Warcraft to work out your rotation and the CC rotation.
What the CC writer then has to do, is compare the given rotation and your in-game logs to determine why 'you' chose to do things that way, and where you differ from the procedural rotation. if that's 340 spell casts in a 4 minute fight, then they have to pore over and work out where things went differently, if that's 914 casts in a 12 minute fight, it's a bit tougher.
this is effectively what HC raid groups do in their spare time, go over DPS logs for periods where they can improve DPS, and go through recordings to work out where they didn't move in time, switched to the wrong mob, didn't use a pot in combat, could have moved to another area, healed a different person, etc.
you might see that you need to move because the boss is about to do some crazy frontal cone/pie attack. HB, will not make that decision because it doesn't see the fire at all, it doesn't use or listen to DBM. that's the player's job. and in general, HB doesn't really get that message, not always. on a few cone attacks, it knows the radian and direction, and will walk out of it, but it can't really strafe properly or, walk through the attack and turn the boss around. woe betide if you pull that shit while tanking and nuke the raid group. the way that strafing works can be a little lacklustre, but, it's always room for improvement. So, while CC's can see the 'telegraph' of the casting bar, and can read the attack, HB won't know where it's going to land until the client does.
in PvP/Arena, there's lots of options in combat that require advanced geometry to work, i.e. LoS casting and strafing out of burst/slows/ blinking behind walls. a bot won't make those decisions, because it needs access to geometry, and an entirely different set of decisions and behaviors, to make it appear human or 'noobish' when it's backing up into walls, tripping into rocks, etc.
TLDR, there's ways to improve a CC, but it requires proving there's a problem, then working out what you want the CC to do differently. any programmer can make changes, a good one works out what you want changed and if it's good or bad.