To answer your question...
The Tampa Bay Buccaneers made Jackson the first selection of the 1986 NFL draft. But Jackson rejected their five-year, multi-million dollar contract. "My first love is baseball," he said, "and it has always been a dream of mine to be a major-league player."
Of course, we all realize that in short time, Bo returned to the NFL with the Raiders. It's very likely, Bo just didn't want to play with the Bucs since they were the doormat of the NFL at the time. However, the quote above is all I could really find that came from the horse's mouth.