Abercrombie Preston blazer sizing question

Hi,
new around here and already a question. I'm looking at one of those
Preston Cord Blazers by Abercrombie & Fitch and I can't seem to figure
out which size I should get.
I'm 6'3" (1.91m) but not very large, almost skinny (77 kilo). I find
that in Polo RL shirts M is a little bit too small and L is largish, but
pretty much right. Same with sweatshirts or pullovers, they're mostly L.
So the $64k question: Can I extrapolate this to the blazer or am I
missing something here? You Americans tend to be bigger you know ;–)
Thanks a lot,
Hans
The Netherlands