Size guides are broken on the BB website. They don't exist. You have to call to get that information. The SA apologized profusely about it when I called to decipher sizes for my boy last weekend. She blamed it on the conversion to the new website and said they hoped it would be fixed ASAP.
Speaking of sizing, what the heck is "Medium" and "Large" in Extra Slim Fit? Extra Slim 15.5x33 and 16.5x35?
The sleeves on the medium ESF sportshirt are a little long on me and my typical size for the dress shirt is 15-33, so I would say that the sleeves are probably longer than 33.