I have the navy version of this from last year, and I remember there were huge size discrepancies between the colors that time too. (I think the lapels were the same on all the colors last year though.)
FWIW, last year I found them all to run really big, just different degrees of big between colors, and to be honest I think the one I have (navy, in petite small) is still slightly too big/sloppy on me.
ETA: It's v. comfy though! I think of it more as a cardigan than a blazer.