A couple reasons:
- Fergie had a return stint with the Cubs in the early '80s, so his total gets boosted by Donruss and Fleer.
- Fergie is a Hall of Famer, and has been included in many of the modern sets. Other than Santo, the rest of the '69 Cubs are rarely seen in modern sets.
My Fergie total is 102 cards. The oldest is his first Topps Cubs card in 1967. The most recent would be a couple from this year. Archives and the Wrigley Field insert set.