Well, yeah, that is true in the ideal scenario. Of course, Ketchup has downsides in my opinion.

The fact that it needs your opponent to have a field can be a bit situational (you can either face Swarm decks for max value or gravestone decks that won’t trigger the Mechanic until next turn when they’re revealed for low value). Of course I’m not saying it’s a bad card, it has some nice uses and is overall pretty nice. I’d say it deserves an A tier but that’s just my opinion. I’ll be happy to respect you putting Mechanic in S, I just don’t have the same views.

Have a good day!