Those two words inspire both dread and hope in football. Fourth down spells doom or saves careers. It can change a game.Or it can be the down where you send on the kicking team.Carolina Panthers fans who have bristled at Ron Rivera conservatism in fourthand1 situations may not take much solace in this statistic: Of the 31 other NFL teams, only one has gone for it on fourth down less than the Panthers since 2011 when Rivera took over.Want to guess who?Denver directed by former Panthers head coach John Fox.Then again, going for it a lot on fourth down does not translate directly to victories, according to an Observer analysis.Of the four NFL teams that have gone for it on fourth down the most frequently starting in 2011, all have mostly languished toward the bottom of the NFL standings.On the negative side, the defense was awful against the pass as the Cardinals racked up nearly 300 yards with four different quarterbacks, all of whom had success against the secondary. The worst part