I agree you should go down a size if you want a slim fit. I bought a large and was glad to see they were running big, because I've put on weight that is showing up in more thickness through my back, bust and waist. But, when I get back to my more normal size, there will be other large jerseys that still fit well, and this one will be too big, eventually.

I will say, though, that even though this one is running large, the armholes still provided enough coverage and so forth. There are no big gaping parts. It is still cut well over all. The extra roominess seems to be just sort of all over, not really sloppy over-sized anywhere in particular.