If + present tense, would + main verb

Hello native speakers, In a different thread on another language section, I came across the sentence "I'd be very shocked if you are who I think you are" that someone wanted translated. The sentence make total sense to me, but non-native speaker thought it better to say ...if you were who I think you are. This to me didn't really make sense because it, for one, mixes up tense agreement, and also because there's nothing hypothetical or counterfactual to warrant the use of the past subjunctive. The speakers takes his assumption to be true. Is there anyone out there how can often a better explanation on this? Actually, the more I turn it over in my brain, the more I want to allow for this possibility.