People didn't watch him play and get gassed because he has a 7-10 three point night once every couple weeks and think that's the norm. Not paying attention to all the 5-16 games with horrendous shot selection and no defense.
The good games and the bad games together averaged to 18ppg on 58% TS% last year. For comparison, D-lo shot 48% TS in the playoffs and Rui shot 47% TS. And they weren't playing no defense either.
Klay can still shoot well enough to help the Lakers. The bigger question is whether they can afford yet another guard who can't defend.