have a question about crappie in a small lake

when i was a kid for 10 years i lived in a neighborhood with 3 ponds the middle one was the2.5 acre lake very deep pond. i use to fish it religiously but only ever caught bream and small bass but tons of bluegill.

never even touched a catfish in it the lake was around 50 years old by that time. nobody hardly fished them at all due to old people living in the area who would run off anyone who would try to. about 6 years into fishing almost daily i see a family fishing one day with jigs and minnows and i swear t god they were catching 1.5 to 2 pound white crappie slabs every 30 seconds casting way out in the middle.

i was like wtf? because i had used minnows in the past before and never caught any even once when the dam busted and the lake was only 25% filled with water just 5 months earlier lol. i even helped them catch some they gave me some minnows and i caught 15 myself within hour n a half

all in all we took out about 60 fish in that 2 acre pond im curious how the lake was able to hold such slab massive healthy white crappie when they dont put any money into stocking it wonder what they were eating