Be fair, he only said that 3 of 15 goals were from corners, that is true.
I think we need to separate the fact that 3% of corners lead to goals.... from the % of goals that come from corners
E.g. if 100% of goals came from corners, we should focus all our attention on them. If 1% of goals came from corners, they are not important.
It is somewhere inbetween and they are important, so we should at least beat the first man and attack the ball properly, nobody is suggesting we solely focus all our play on set pieces like Pulis, nobody is saying we should commit all 10 outfield players into the box, but we definitely should do better with corners.