1.) the bezel took up a greater % of the diameter of the watch (ie this is a relatively “thin bezel”)
If you think about the most desirable models - 2499, 5970, 3970 - the bezels (ie the precious metal) on those watches are much wider than the 5170 relative to the total size of the watch (and therefore the dials are relatively smaller). The 2499’s popularity tells us the ideal ratio of bezel to dial is idk 75%/25% vs the 5170 is (I’m making this up) 90%/10%
2.) the bezel was a little more sloped (it wears more “flat”)
Same thing as above - those PCs have much more slope than the 5170