Rival defensive coaches believe Chip Kelly can once again make Colin Kaepernick one of the NFL's most dangerous quarterbacks.

"I think [Kaepernick] is a good enough passer, but obviously what'll be a nightmare is his ability to run," on defensive coordinator said. "That offense is straight 'Freddy Krueger' when you have a quarterback that can pull the ball and run at any given time."

Kelly's offense stalled with the Philadelphia Eagles when he didn't have a quarterback capable of pulling off the second part of the zone read.

"The fact that Kap can make guys miss and get in the open field, they didn't have that last year at all in Philly," another defensive coordinator said. "We treated [Sam] Bradford like he was under center. There was zero threat of him running the ball. We told our guys, 'Don't treat him like he's in the shotgun, he's never gonna pull the ball.' "