Starter size is dependent upon the volume and starting gravity of your recipe, and the age of yeast. If your recipe is particularly high gravity, the starter size will be larger to grow more yeast cells to handle the amount of sugars in your wort. Also, the yeast counts for lagers is higher than the yeast cell counts needed for ales, due to the fermenting temperature difference and the activity of the different strains.
If you are concerned with adding that size starter to your wort, just cold crash your starter for a day or two and decant most of the fluid off the top. Bring your cold yeast up to room temperature gently and pitch.
I do this with all my starters, big and small to minimize any flavor impact of the starter wort on the main batch.