The thing is, Kaladin is really tall. He's freakishly tall. I think Brandon said he was almost 2mt tall, which is mind boggling to me.
We don't have a precise canon height for Gaz, but he's shorter than Shallan, who's, if i recall correctly, around 5'6.
Sometimes i have to decrease this height difference simply because i have to fit them both in the same picture, ahah.