Maybe most times lack of height won't hurt us, but to your point about being a perfectionist he does see things that can harm us even though we win most games. Against Watford in the league we won 3-1. Even though the game was done and dusted Watford lumped a goal kick which Kompany missed and Deeney headed it directly into the path of Deulofeu who slotted it home. If we have situations where we are winning by 1 goal lots of these teams will revert to lump ball and it can cause problems for us. There's been some set pieces that hurt us. Chelsea's 2nd goal at the bridge. Brighton when they scored 1st on the last day. It's not only about headed goals. Rondon bullied his way to getting a goal against Newcastle. I'm sure Pep looks at a lot of situations which never actually leaded goal, but was a clear shot that the opposing player just missed and thought that we need to prevent that from happening.