Complex sentence: Drafted first overall in the 2001 NHL Entry Draft by the Atlanta Thrashers, he began his NHL career in 2001--02 with Atlanta and was nominated for the Calder Memorial Trophy as league rookie-of-the-year.
Split into simpler sentences: Drafted first overall in the 2001 NHL Entry Draft by the Atlanta Thrashers, he began his NHL career in 2001--02 with Atlanta. Kovalchuk was nominated for the Calder Memorial Trophy as league rookie-of-the-year.