"Substantial progress" has been made in the effort to keep the Preakness Stakes at Pimlico Race Course in Northwest Baltimore, according to a letter received by the Maryland Racing Commission from the team negotiating a possible deal. The Aug. 13 letter provided no further details beyond saying the team hopes to make recommendations "as to the ways and means to preserve the Preakness Stakes at Pimlico and year-round sustainable racing at Laurel Park." Despite its vagueness, the letter represents…