It's three years / $15.25 million for Hyde, with $6 million guaranteed. Another $2 million guarantees if he's still on the roster three days into the 2019 league year:
https://www.dawgsbynature.com/2018/...n-of-rb-carlos-hydes-contract-with-the-browns
That's nowhere near as crazy as, say, the Jerick McKinnon deal in SF and yes, they can absolutely let him walk after a year - though the Browns have enough cap space to be able to afford letting just about anyone walk if they don't like them. Remember how they were willing to eat Brock Osweiller's insane salary just to get the draft pick that came with him?
My question would be is Hyde really that much better than, say, Isaiah Crowell, the guy he's replacing? This is a pretty deep draft class for running backs, even if they don't get Saquon Barkley. Two of the best running backs in the league last year were rookies who weren't even day-one picks (Alvin Kamara and Kareem Hunt).
At best they've secured themselves a slight upgrade on what they had last season in Crowell, but they could probably have gotten the same outcome or better for much less.