Simplify the following text for a Grade 10 native English-speaking person.
Original: Before joining the NHL in 1988 , Linden helped the Medicine Hat Tigers of the Western Hockey League ( WHL ) win consecutive Memorial Cup championships .
Simplified: Before he joined the NHL in 1988 , Linden helped the Medicine Hat Tigers of the Western Hockey League ( WHL ) win the Memorial Cup , the trophy for junior hockey teams in Canada , twice in a row .