Yes, the central defence, or the whole defence, is the only part of the team that is performing well so far of the season.
I think you see things that aren’t there, maybe because you dislike him and would like him to fail. I have not seen him being out-muscled more than others. And being a nervous wreck?. If that was the case, they wouldn’t have one of the best defensive records in the PL so far. Heading the ball is maybe Lindelof’s biggest weakness, but for being his biggest weakness he has done ok so far. He has 3.3 won aerial duels per match and 2 lost (won 62% of his aerial duels). Compared to Smalling’s last season, where heading is his best ability, won 4.3 per match and lost 2.4 per match (won 64% of his aerial duels).