3 Legendary in a row...and I got only one of them...

Well that's just bad luck for you mate.

that's why you should always keep some money in the Steam-Account, to get yourself at least a 1-Dy-Premium, whenever you got a Legendary.
I got the Legendary Shotgun this Weekend in the Premium-Line, so forking out some Euros for Premium was quite useful

yeah, or just pay the super cheap fee of 50 dollars and get premium forever and ever

2 bad, which three legendary you got

Its awnfull

However, you are lucky)

I have only one dropped out, and it is very rare

ive gotten mvp 9x in a row and leveled up in the process so total of 11 proto crates and i didnt get shit. To get legendary from a box for me takes me about 100 mvps or 100 proto crates.