Complex sentence: In contrast to the local legend, the mascot was not inspired by the Houston Oilers professional football team (the school was established 25 years before the team), instead it is a tribute to an important sector of the local and regional economy.
Split into simpler sentences: In contrast to the local legend, the mascot was not inspired by the Houston Oilers professional football team (the school was established 25 years before the team). Instead it is a tribute to an important sector of the local and regional economy.