Davis sees the tackle slant inside of him, then jumps to the left. By now, Davis should realize he's supposed to switch. Davis never engages though, and while he's frozen for a second with no one to block, the LB loops around his outside shoulder and makes the sack.
If Davis doesn't flinch when the tackle slants inside him and instead just stands there, the LB would have had to take a wider path. I don't blame him for flinching, but he sure took a long time to figure out what was going on.