Complex sentence: According to retrosheet site, he was signed in 1961 as an amateur free agent by the Washington Senators; this would have been the expansion team; the team that was the Washington Senators in 1959 moved to Minnesota during the 1960-1961 offseason.
Split into simpler sentences: According to retrosheet site, he was signed in 1961 as an amateur free agent by the Washington Senators; this would have been the expansion team. The team that was the Washington Senators in 1959 moved to Minnesota during the 1960-1961 offseason.