If you put it that way, yes, it’s silly. The thing is, CP3 is a better at defense by advanced metrics (and eye test)than Beverley; the proven scorer is redundant with your sixth man of the year (even if Gordon is injury prone); and D’Antoni’s system makes Dekker look probably better than he is.
Now, CP3 and Harden probably agreed to play together before this deal happened. So they envision how they are playing together. This is not like a Rondo-to-Dallas situation. It was basically a free agency move.
My guess is: they will figure out how to play together just fine. They are both high IQ players, and very versatile. And CP3 is probably taking the backseat is saving his legs to the playoffs.