The only time I can think of where the jury really voted based on game play was season 10. Michelle and Ollie both hated Dan, but voted for him. Jerry was friends with Memphis, voted for Dan. The thing is, Shelly does not have the natural charisma that Dan had, nor the challenge winning ability. Jordan is a bigger threat. Shelly's game really fell apart this last week.
I say toss Adam. I like him more, but he might be able to beat Jordan or Rachel. Shelly will only win a challenge if they announce a "Smoke 100 cigarettes in five minutes" challenge.