Well ok. Even feeding hoppers it seems odd they'd be that size.
BPs eat hoppers fresh out of the egg, typically only for their first 3-5 meals, before moving up to small adult mice or being transferred to rats. So the breeder suggesting fuzzies seems very odd, especially for well established yearlings.
At that size and age they should be on large adult mice or small rats by now. With juvenile and sub-adult BPs you want to shoot for prey 10-15% of the snakes body weight.
Fuzzies are 5-7 grams. Small rats are 50-89 grams. HUUUUGE difference.
So at 700 grams a fuzzy is less than 1% of the smaller snakes body weight. The 900 gram guy is getting a fraction of a percentage of what he should be eating.