Jambon’s comment about the seat tube is spot on. Yetis do seem to come up quite big.
I went from a size large Commencal Meta 5 to a medium Yeti ASR-5. The Yeti is actually larger in both seat tube and top tube size, although the Yeti’s seat tube is steeper which effectively shortens the top tube a bit.
For what it’s worth I’m 6 foot tall, and Yeti recommend a large for me. I’m glad I went for a Medium – it’s perfect for me, although I never tried a large and I suspect that with an appropriate stem that would be OK too.
I spent ages deliberating about which size to get – it got a bit anal with spreadsheets for various quoted top tube lengths. Long story short, a Yeti medium is longer than any other medium frame I could find, and a lot of manufacturers’ large frames, too.