I assure you its just an impression. Line splitting passes are Otamendi's strength. I guess he has the advantage of playing on the left with his right foot. But even if you account for that advantage, I think he is simply more aggressive and thus just better.
I know its wierd for people to realize it. But So es does more ball rotation passing. I.e what Yaya used to do with the 1 touch short pass move and retrieve stuff.
Otamendi actually often aggressively carries the ball forward then make a defense splitting pass. He also commits more errors too because of it. Hence why Stones pass% is 97 to Otas 91.
But when you look at forward passes, key passes, passes into the attacking 3rd etc. Its not even close. Otamendi is leaps ahead.