Simplify the following text for a Grade 11 native English-speaking person.
Original: In 1990 , Sergei Makarov of the Calgary Flames became the oldest player , at age 31 , to win the Calder , even though he had played for the `` unofficially '' professional team HC CSKA Moscow ( the `` Red Army '' team ) in the Soviet Union .
Simplified: In 1990 , Sergei Makarov of the Calgary Flames became the oldest player , at age 31 , to win the Calder , even though he had played professionally in the Soviet Union as a member of HC CSKA Moscow .