this from Faith and Theology to understand this cryptic comment.
The same could be said of the sacraments. The sacrament's efficacy is due to the presence of Christ and nothing else. Preaching that is helpful isn't helpful because the preacher is a good preacher, and the Eucharist's effectiveness is independent of the holiness of the priest and congregation. People come expecting to receive, and Christ is gracious enough to be present, in word and sacrament.