The key thing in that comment was "replacement to Carson"
Carson couldn't catch, and we lost goals because of it. Myhill can catch but often doesn't and we lose goals because of it.
Nobody's going to say Myhill is one of the best in the league, no one's going to say he's above average for a no.2 but he's ours an he's doing his job to an acceptable degree now, whereas in the past it was his fault. there aren't many (if any) of the goals that can purely be put down to Myhill in the last three games.
Chelsea: deflection off Jones otherwise caught
Sunderland: deflection and was wrong footed, Great save but let down by Sessegnon's marker
Swansea: that was just bad defence. period.