Birdcage is unbeatable, unless Doffy is defeated, nd if somehow doffy fly outside the Cage I bet it weakens, if not he would hv left the cage to buy time from luffy Gear 4th attacks, so doflamingo knws this facts that is why he won't take on an opponent he knws he stronger than him, nd again, Doflamingo is already at Admiral level, you guyz jst don't realise that.
His Haki is strong he even hv CoC, nd reached his awakened form of his devil fruit, Doffy has no Room for improvement, he has already reached his ultimate form of strength, he already withstood attacks that can kill an Admiral.
Akainu might die from those attack becouse he doesn't have healing powers, especially from Law attack, yet doffy survived it, the only thing akainu could have done is indure it then later die, like how Whitebeard indured all those damage, he knew that he would die even if they escaped that is why he chose to stay behind and save evryone.
But Doffy is not dyin, so it clearly shows he is at a level even the Admiral might not beat him, I highly dought Fujitora might beat him, we all knw that Doffy planned to kill fujitora right...
So it clearly shows he is at Admiral Level, also one of the guys who left Marineford war withut any scretch on him....even Aokiji respected him, as he avoided fightin him, they both knw if they fought it would cost them both,
Doffy jst beat smoker like he was not a vice admiral, like he was jst a marine regular soldier, beat Law like he was not a ship Captain, so far only Gear 4th attacks worked on him nothing else
Doesn't dat make him Admiral level....Knwing that Gear 4 has drawback means that if Luffy somehow manage to perfect it then he might take on an admiral and Yonko using it, coz it has strong attack, Oda made it clear that Gear 4th is Admiral level, it only needs to be perfected, and by the way the gears wil end up at Gear 5th, then that's that.......Gear 5th plus awakening wil be able to take on Blackbeard at full power.