Here is a truism...: Pastors and elders must regularly discuss both the quality of the worship services and the pastors' sermons. Most councils now have a small task-force that periodically talks with the pastor about the effectiveness of his/her sermons. Calvin Seminary has evaluation sheets which can be helpful both for the elders (and members) and the pastors.
But there is also room for you personally as an elder to talk a bit with the pastor confidentially about the challenge of bringing the Word.
Here is a story that illustrates it.
It concerns the Rev. Clarence Boomsma who passed away a few years ago. Clarence is widely remembered as a devout believer and a capable pastor. Boomsma began his ministry in Imlay City from which he went to the Calvin CRC of Grand Rapids, 1948. His ministry spanned forty years during which he served two congregations. From Imlay City, MI, he went to the Calvin CRC of Grand Rapids which he served from 1948 to 1983 when he retired.
He once told us a story that I may share with you here. He said that after he had been in Grand Rapid for a few years, he had a visit from an elder of Imlay City who stayed for the weekend (Clarence was then still a bachelor). Over coffee they discussed the sermon. After a while the elder looked at him earnestly. 'Clarence', he said, 'your sermon this morning was not as good as I had expected. You seem not to have grown '. “
Clarence said to us, “That remark stayed with me. I had been given a lot of compliments. Those I soon forgot. This earnest assessment of this elder whom I esteemed cut to the quick and stayed with me all my life. I began to evaluate my sermons carefully. I worked at them harder. I learned to recognize sermons that were not as good as they should be. I sought feed-back... I owe that elder a great debt of gratitude.”
Perhaps you as an elder may also find a moment with your pastor at which you can speak a personal word of commendation but also give some honest advice. And remember your pastor will always appreciate discussing the needs of the congratulation and whether he addresses them effectively.