If your sleeve cast-on is wider than you expected, there are two possible explanations!
First, full-length sleeves do give several inches of ease in the wrist. The reason for this is to give an impression of a more gradually-shaped arm. Very narrow sweater wrists tend to focus the eye there, and make the biceps look larger than they actually are -- a little ease is a powerful thing! You can read more about this in our Fit Philosophy.
Next, it's possible you chose a straight sleeve. In CustomFit, a straight sleeve is a sleeve that contains no shaping. A tapered sleeve is slimmer at the wrist than the bicep. If this is the case, and you intended to choose a tapered sleeve, please get in touch with us!