Complex sentence: Analyst Jackie Stewart was to be the color commentator, but was only able to be at the grounds on Monday and Tuesday as he left the Speedway Wednesday for Formula One commitments at the 1973 Monaco Grand Prix.
Split into simpler sentences: Analyst Jackie Stewart was to be the color commentator, but was only able to be at the grounds on Monday and Tuesday. Stewart left the Speedway Wednesday for Formula One commitments at the 1973 Monaco Grand Prix.