0 of 6

Tom Szczerbowski/Getty Images

The average progression of an NBA career features incremental annual improvement that leads to a peak stretch (right around the mid-to-late 20s), and then inevitable decline before retirement.

Players grow, thrive then fade. It's the circle of NBA life.

Sometimes, for whatever reason, verified talents peak before they can reach their full potential, be it due to poor health, a trade or a simple inability to develop their game. These situations can be disappointing and even sad.

But they also highlight how ridiculously difficult it is to have a long, fulfilled NBA career. Here's a look at seven players who qualify. Each of them accomplished quite a bit, but they also left plenty of individual production on the table. Most either played on an All-Star team or won a major award before their 25th birthday, then either dramatically declined or failed to improve in any noticeable way.

There are no anomalous breakout years, but instead a clear uphill trajectory before unexpectedly leveling off. They're listed in alphabetical order.