Herein lies the problem. The issue is not that he didn't direct the header; no, in that instance he did as well as he could have just like anyone else. It's the fact that he shouldn't be contesting a 50/50 header in the first place. He should have been on his toes to challenge/pressure/jostle and make it hard for KDB to influence the very first (bouncing) ball. By letting it bounce, he can only go for a 50/50 aerial or jostle from a standing position. By pressing against KDB or the ball, he can make it an awkward header/control; it's something Martinez does to a high standard. It's a small error in isolation but not when it comes to Lindelof. It's extremely consistent of his passive nature (just look the examples I have given) despite what the last 10-15 games have told us and the incredibly roundabout ways some posters have been using to absolve this tendency:
"He wasn't told by coaches previously to be proactive and aggressive"
"Varane and Martinez conceded 6 goals against City (despite Lindelof coming on and conceding three with him on the pitch but you know, let's ignore facts) so therefore this means Lindelof is just as good as anybody else"
"It's the midfield's fault"
You can look up my post about Casemiro, where I've basically said it was a one-man midfield. Besides, I'm not blaming the loss on Lindelof. I'm blaming Lindelof for consistently underwhelming me and always flattering to deceive after a run of form. I'm basing this on 6 years of rinse, repeat and not 10-15 games cycles.
As for the last line, it's funny how you turn the moral cheek after I call you out on it. That's good, at least you can show some growth, unlike our melting Iceman.