Pretty dependent on your definition of "failure." If its fail to make the majors, then yeah its a pretty low risk for a guy like Anthony. If it means being a good player that you're happy you planned around, there is a pretty significant risk. Tons of examples of incredibly highly regarded young prospects who had success at young ages in the minors who never became even average regulars.
If we look at Xander's SS prospect grouping (Profar, Machado, X, and Sano). Jurickson Profar was a unanimous top prospect for two years in a row and is now 32 and has exactly one 2 WAR season which took him 7 MLB season and three teams to achieve. He posted a 280/370/450 line at 19 years old over 500 PAs in AA showing possible 60 defense at short. Sano was a consistent top 10 guy and couldnt even stick at third and never really learned to hit major league pitching. Roman has more defensive ability, but even a guy like Profar who was supposed to be a plus defensive SS who had a full season of elite offensive numbers at AA at 19 ended up being a journeyman. If that's not a failure, then I'd agree the risk is pretty miniscule that you get much worse than that, but if youre planning around the guy, thats an objectively pretty bad outcome.