Boston was kind of a freak thing with the Thornton trade and injuries.
- Thornton dealt mid-2005/06 which paved the way for more opportunity for Bergeron; there was so much uncertainty coming out of the lockout, but even after Bergeron had a really good rookie year and an even better year in the AHL, the plan coming out of the offseason before injuries/trades was to have him as the 3C behind Thornton and Zhamnov
- Savard signed in the 2006 offseason to create a top 6 dynamic with Bergeron
- Bergeron suffers serious injury at the start of 2007/08 and wouldn't start rounding back to form until 2009/10, which paves the way for Krejci to form a top 6 dynamic with Savard
- Just as Bergeron is rounding back to form Savard suffers huge injury/injuries that essentially completely halt his career for good
- Bergeron and Krejci form a top 6 dynamic for the next decade which hasn't been challenged at all, even though roles have shifted between them as the decade went on
Dealing a player or having injuries occur just creates the opportunity to get better, but a lot of it is just luck.