You've got to have all sorts of contingency plans.
I'd imagine that Miami can get Devonta Smith with that Houston pick if they want him. But with that second pick in the 1st round, I would have my eyes on Najee Harris and Zaven Collins, but don't have a lot of faith that we'll actually get a crack at either one. That's where you start looking at a Creed Humphrey as a backup plan.
And I wouldn't necessarily give Karras the boot. He's been playing pretty well, IMO. And I think he's developing some chemistry with Tua, despite a few bad snaps. I don't know that breaking in a rookie Center is the right thing for Tua when he's so young, anyway. You'd like to have veteran eyes ID'ing and calling out the blitz looks while Tua is still young. I think Humphrey could easily slide in at LG or RG, wherever you need him. Options are good to have.