Maybe, maybe not. But the Red Sox won 108 games in 2018 and looked destined to dominate for years to come, too. And then they played like a .500 team for a good portion of 2019 and fired their GM.
A lot of things can go right or wrong in a very short period, let alone nine years. Teams can make signings, players can have break out years or decline, farm systems can change, etc. etc.
Only time will tell whether Cole truly made the right decision (hopefully he regrets it).