What an odd career, huh? He peaks in years 13-16! But what if...
Ok, that's weird.
Don't let Gary Sheffield's career WAR of 66 over 22 seasons fool you (as if that were something to sneeze at). He was in the thick of things throughout his career -- even if he did it backwards. But good enough for the Hall of Fame Zone doesn't necessarily mean good enough for the Hall of Fame. Does it?
Method, developed HERE:
...I decided to take the same set of players and find another Hall of Fame Zone--the Hall of Fame Career WAR Arc. I took every player and arranged his career WAR numbers (via Fangraphs) from his first season to his last. I found that the average Hall of Famer has a 20.5-year career. That surprised me a bit.
With the career-aligned data in place, from each of their rookie seasons to their sad departure from the majors some 20 years later, I averaged every year's WAR data. Obvious note: while almost every hall of famer starts with a modest 1.0-ish WAR, they adjust very quickly, up into the 5s and 6s in just three years. Even if you've been following sabermetrics for some time, you might still be surprised to note that the average hall of famer peaks in his 7th season--somewhere between 26 and 28 years old.
With the average hall-of-fame WAR for each season of the "average hall of famer" in place, I then found the standard deviation for every season, then added and subtracted that amount from each respective season. I plotted the data and found a polynomial (^4) line-of-best-fit for each line: one line for the average, one line for the lower standard deviation, and one line for the high standard deviation.
Data: Fangraphs for WAR, B-Ref for counting stats.