“Too often, we overlook the value of imagination and dreams and the _____. fill in the blank and we can prove we did a good job.” is gauntlet the author has thrown to all of us.
If you choose attitude, as is indicated by Shri Tanmay Vora, in his blog-post “the Attitude of Quality”, then ‘people [and their attitude] are at the core of excellence.’
I would put my bet on Commitment [or Determination] of Action. A dream not supported by a determined action, arising from a dogged commitment remains a dream only, and not the reality of success.