Twenty Fourteen theme loading full-sized image as thumbnail, then re-sizing

Basically, I got the exact same problem as the guy in this post, but I see that there are still no solution as of yet.

Does anyone have a solution to this? The way this theme is set up, it serves the full-sized image on the front page, but I need it to serve a scaled image on the front page and a full-sized image in the featured post.