#12 - Ron Gant: 5 years, $33 million, 1996
Ron Gant was an excellent player for the Braves and Reds before signing his first long-term deal with the Cardinals prior to the 1996 season. He was a two-time All-Star, finished top 14 in MVP voting four different times, and was ready to add even more firepower to the Cardinals' lineup.
His first year in St. Louis was great, posting a .862 OPS with 30 HR and 82 RBI, but his OPS dipped down to .698 in 1997 and then he fell out of favor in the clubhouse in 1998.
The Cardinals ended up trading Gant to the Phillies before the 1999 season, agreeing to pay half of Gant's salary in the process. It's safe to say the club had much higher hopes for how that deal would turn out.