OK here's the scoop. The Starter Rating is a mechanism to help ease players who don't have an established rating into the system.
You can think of it as a best guess of how the players plays. That best guess could come from known ability, rating in some other system, limited evidence, etc.
Generally local knowledge is the best. So, for example, for the Omega Billiards Tour in Dallas, each of the old Omega Ratings, 5,6,7,8,9...was translated into a starter rating. Many Arizona ratings have been translated into starter ratings, as have ratings from various league systems. This is the mechanism for a new league manager to start players at a sensible place. Then of course once a player has 200 games those training wheels are forgotten.
Amongst the crudest of such assignments is the old CSI category of "Open" being 525. We all know some of those former opens actually play below 400 or in the high 600s.
Once people get some games in the system, we start to get some inkling of whether they are above 525 or below 525. In your first example, GJ, he has 100 games playing at 602 speed. So we don't move his starter rating all the way up to 602, but it's looking pretty clear he plays above 525 speed. In the second case the player has 28 games at 492 speed. Not much information but enough to nudge the starter rating down a bit. There is an algorithm that takes into account how far from the former starter is the performance and how many games are played.
Sounds like a good change. Thanks for doing this.