....Goff did play poorly, but the RB's do seem to be a mess from time to time and SF knows Kupp and Bobby Trees like a book, so perhaps they know the patterns they run seeing them twice a year and having two weeks to prepare; so not a lot of separation sometimes.
Still, that is why QB's make obscene coin; you gotta be an encyclopedia of the offense, know your reads, know when to throw, etc., and the TYPE of mistakes Goff made (not that he made mistakes) should not happen (the really bad INT's and ridiculous fumble), and they are happening in droves lately and sinking a Super Bowl-level defense IMHO....
