@MonkeyDMalcolm:
1 black beard isn't an offical shichibukai
HONEST!!!
2 Stop speculating
Shanks (a yonkou) used to rival Mihawk, until mihawk was proclaimed the best swordsman. Shanks lost to mihawk or shanks is no longer able to rival mihawk due to having one arm.
Choose one because mihawk is the best now.
Blackbeard scared shanks (a yonkou) proving he is able to fight on their level.
So there's no speculation here, try taking your time before posting rashly.
3. we don't know if the balance have been disrupted because oda hasn't shown us the after math of what luffy has been doing.
That's why it is safe to say the balance hasn't been shifted, when he shows us it will completely disprove people saying it hasn't.
4. it hasn't even been shown if Black beard beat Ace so all your theories and speculation are for not.
First of all it's kind of obvious ace has been beaten, but I'm not using him as an example.
A non-devil fruit Blackbeard scared shanks in a fair fight, it proves he is able to fight on his level.
So there is no speculation in my post, get your facts right next time.