I disagree with this comment. If anything, I noticed that the right shoulder overhangs a smidge. So the younger brother has one wider shoulder? I don't think the length is bad. In a super conservative/classical sense, maybe. But for a casual jacket, the length is modern. How open the quarters are is a taste preference in my mind. Perhaps these being so open and showing the sweater makes it appear smaller.
I understand. So, no for shoulder fit and fit across his hips? I would agree.
I think the open front quarters may be a symptom that is mirrored by an open vent in the back, although we cannot see it. For someone that appears to have relatively wide hips, a "modern length" may not work if the jacket isn't ventless and his bum properly covered by the less than fashionable length.
This potential and unvisualized problem is the possible outcome of following modern fashion, when one should maintain a certain less fashionable style for best effect.
Overall, a less fitted sack type cut would probably look better,
The visible sweater is probably a partial effect of wearing trousers with too low of a rise, another modern fashion that few can use to positive effect. This almost never looks good when combined with a blazer or sports jacket that will be buttoned at some point or standard length waistcoat/vest cut for a higher rise; i.e., no one should see your sweater, longer than standard waistcoat, shirt or belt buckle when the jacket is buttoned. Is a ridiculous look and you might as well unzip your fly to complete the effect.
Within the context of a wintertime evening casual dinner where the plan is then drinks with the boys in what I remember as NYC, this outfit from blazer to khakis, just doesn't work for me..
It looks to be summer daywear that is being stretched into a cool early evening or waterfront event or with the addition of a sweater and has the added limitation of being acceptable within a narrow construct of what might otherwise be termed preppy. The pocket silk pocket square gives rise to the idea that this outfit is to impress someone other than the guys. Hence, my "Chip" and librarian cracks, recognizing the use of a poorly fitted outfit suitable for a very different context, since even an ardent prep stylist would not wear such an outfit for the intended purpose of a wintertime casual evening dinner and pounding drinks with the boys in The City, at least not the ones I hang with.
Southstreet Seaport at 6pm early in June with Lauren for appetizers and drinks to be followed by drinking with the guys after taking Lauren back to her place for a more or less successful wrestling match on the her couch? Yeah, it works, but only if the outfit was properly fitted; i.e., not fashion forward.
Executive Summary: we agree the jacket looks as if was tailored for someone else with a completely different build.