That's like wondering because Sirianni knows the ingredients Indy needs to make a great carrot cake on Indy, understanding what he needs to make a wonderful tomato sauce on Philly, will somehow screw Indy's carrot cake up.
Mariota has already been rumored to be on the chopping block in Oakland because of his cap number.
I also think you might be over est JB value to teams. Dont see a team that will sign him as a starter. Only chance would be a team that has a QB injured.