Is Bradford's production done in a vacuum though? Look at each year and each team and it isn't hard to understand why he hasn't been productive.
Look at just last year. Kelly's system has been less effective each year. Kelly wasn't ready to be a GM. Kelly got rid of key pieces of what success he did have. LT Peters was hurt throughout the year and less effective. Evan Mathis was cut. LeSean McCoy was cut. Jeremy Maclin was let go. Agholor was a rookie and not ready. Bradford was coming off of injury and in a new system(again). Murray was a HORRIBLE fit for that system.
To me, any reasonable view of that situation would determine that it wasn't going hit the ground running so to speak, and probably wouldn't be real productive.
Bradford will probably need a half a season to catch up with the Vikings but hopefully not.