Complex sentence: O'Neal joined the Boston Celtics prior to the 2010--11 season, in 2012, he signed with the Suns, and finally, in the offseason of 2013, he signed with the Warriors.
Split into simpler sentences: O'Neal joined the Boston Celtics prior to the 2010--11 season. In 2012, he signed with the Suns, and in the offseason of 2013, he signed with the Warriors.