Cookies (not your Cookie, another cookie. Uncle probably knows who i talk about) made a bot that would kick a player off the server if his skill level was too low.
If you can kick someone cause he isn't playing well enough, then it should be possible to create a bot that would activate if certain team isn't doing so well, and swap players from one team to another to balance things out.
That part is probably the easiest part. The hard part actually is how to make the bot stop. If it transfers too many good players, the game will just turn into one team destroying the other in turns. If it doesn't transfers enough players then it didn't change much.
So the main problem is how to create a "smart" bot that can determine how many players need to be swapped in order to create 'balanced' teams.

@slap: i agree with uncle. It is cheat for stopping player from defusing bomb. That's it.

Wait what?? maybe i didnt understand. He didnt want to make it available for all, or did he?

Hmmm can't we just make bot get average xlr skill of both teams, if one is more than 50 (or 100) bigger then another, it switches players so average skill would be best possible (closest). That way it will never go too much. Hmm how about script is event which is run when one teams leads for 50+. If it was run once in map, it won't activate again (Sometimes new teams need time to balance).

There is a lot of variables that need to be taken in account. In my opinion the switching of players would be so frequent it would only piss off people cause they're being switched all the time.

Well do you have some actual code? I didnt write any plugins yet..

The easiest i can think of now is (players KD)+(players KD actual in map)=P, // maybe add skill too
if the difference (D) between the sum of each team is higher than X (constant) then it will find 2 players, each from another team, where |P1-P2| = D/2 then you switch them...