Complex sentence: From 1997 to 2003, Treu was the reserve center behind Barret Robbins, but when Robbbins was injured during the 2001 NFL season, Treu capably filled his place during 14 games.
Split into simpler sentences: From 1997 to 2003, Treu was the reserve center behind Barret Robbins. But when Robbbins was injured during the 2001 NFL season, Treu capably filled his place during 14 games.