I think you are overthinking this. Mayfield has a gunslinger mentality. OBJ can beat anyone in a jump ball type scenario, and frequently he can beat any two guys in those scenarios. What's the point of having an all-world WR if your QB is too gun shy to let him make a play (think Brock Osweiler's impact on DeAndre Hopkins).
This marriage is closer to perfect than you've led on. The only argument you've really made here is that Mayfield is too short to throw slants and such over the middle, but Drew Brees is shorter than Mayfield and manages just fine with those routes. Again, I just think you've gotten too microscopic in the analysis.