Complex sentence: In his first season in North America, Ullmark attending the Sabres training camp and after his recovery from an early injury was assigned to begin the 2015--16 season with AHL affiliate, the Rochester Americans.
Split into simpler sentences: In his first season in North America, Ullmark attended the Sabres training camp. After recovery from an early injury, he was assigned to begin the 2015--16 season with the Rochester Americans.