i find it hard to believe that you can grab rim at 5'10" and 50 years old. if you can, thats incredibly impressive! i also may have to call duck tales on you dunking at 5'10" even if you were in your prime. you must be exaggerating on a "little loose", maybe it was five inches below regulation.
The bolts were loose, so it probably played an inch or two low, but it was a regulation height rim. Many factors were involved, including motivation. I was at the "Quad", outdoor courts on the south side of U of MD. campus, playing a game with a couple of old high school friends. Both of them were really good athletes, had played varsity sports (one played college baseball) and a level better than me. But I had been playing a lot of basketball (instead of studying) and had improved a lot, and wanted to impress. I got a breakaway, and Todd yelled out "DUNK", so I went for it. Maximum effort, but noboby was more astonished than me when I rammed it over the front of the rim and down. They probably think I did that all the time! Usually when I'd try, the ball would just slip out of my hand.
When 48, I was playing a lot (lunchtime at work, gym near our workplace) and it came back pretty well, so that I could get rim every outing, though not every leap. Just barely getting it, had to time it right. But now I have to warm up quite a bit, can't just walk out there cold and try, I'd be a foot short. That's another aspect of aging, you really have to get muscles warmed up before max performance is possible.