Complex sentence: Valenzuela's efforts made him the odds-on favorite to be the league's top rookie in, and he didn't disappoint, starting the season 8-0 with five shutouts and an ERA of 0.50.
Split into simpler sentences: Valenzuela's efforts made him the odds-on favorite to be the league's top rookie in. He started the season 8-0 with five shutouts and an ERA of 0.50.