Jeremy Piven -- Cubs Will Win It All ... Thanks To Will Ferrell

Congratulations to the Chicago Cubs ... Jeremy Piven says you're about to end one of the most legendary eras of futility in the history of sports ... and it's all 'cause of Will Ferrell.

Piven was out in NYC when we asked the Chicago born star if this is the year the furries from the midway finally get off the schneid and win a World Series.

Check out the clip -- Jeremy (Ari Gold, let's be real) says the Cubbies got it in the bag and its Ferrell's spring training antics that broke the curse.

FYI -- Ferrell spent some time as the Cubs 3rd base coach during a Spring Training game earlier this month ... and it was hilarious.