Chambers deal is different from Johnson and the others' deals because we are paying a two tier bonus. Meaning he gets some of it up front this year, and some it at a pre-determined time in the future.
This makes the deal slightly less attractive. The money is not quite guaranteed so if Chambers blows his knee apart and can't play again this yer. He won't get that second bonus.
It is something Miami likes to do with their FA's and I think it's smart.
It's one of the main reasons O-Gun hasn't signed yet. He doesn't want that kind of bonus, he wants it all up front at once.