Apparently he wasn't able to handle the end of his baseball life as well as he'd played the game. His reputation became tarnished in later years as stories of infidelity, alleged sexual assault, and bizarre hehavior began coming out. People who'd admired his skill and joie de vivre, as I did, stopped paying attention.
Puckett had a massive stroke over the weekend, and died today. He was only 45. It's such a shame. He was a joy to watch.
eta: There's a great post by Batgirl about Kirby here.