With today being the NHL trade deadline and the St. Louis Blues deciding whether to be buyers or sellers this year, let us look at some of the Blues' worst deals on or near the trade deadline.
1. Ryan Miller

During his time with the Buffalo Sabres, Ryan Miller was one of the NHL's elite goaltenders. The 2009-10 Vezina trophy winner was as consistent as they come, posting a .910 save percentage or better in 8 of his seasons in Buffalo and a career-high .929 save percentage to go along with a career-high 2.22 goals-against average in that 2009-10 season.
It seemed like a perfect trade. The Blues needed a true number-one goalie for a deep playoff run. Meanwhile, the Sabres were rebuilding and looking to add draft capital. The Blues broke up their goaltending duo by trading Jaroslav Halak(Who ended up getting flipped a week later to the Washington Capitals), Chris Stewart, William Carrier, a first-round pick in 2015, and a third-round pick in 2016 for Ryan Miller and Steve Ott. Steve Ott played parts of three seasons in St. Louis and later became an assistant coach with the team, but the focal point of this trade was Ryan Miller.
Miller played 25 games, including playoffs, in a St. Louis jersey and left for Vancouver in free agency. Miller's numbers dipped following the trade to St. Louis and struggled in the playoffs, posting a .897 save percentage and 2.70 goals-against average. The Blues went out in the first round. It is safe to say the trade did not end the way the team dreamt it up.
2. Adam Oates

The St. Louis Blues acquired Adam Oates in the summer of 1989 from the Detroit Red Wings and immediately had a great connection with the Blues star player Brett Hull. In their first season together, the duo scored 215 points combined, with Brett Hull setting a then-career-high with 72 goals and Oates setting a then-career-high 79 assists.
Their second season together was even better, with Hull setting his career high with 86 goals and 131 points while Oates put up an outstanding 90 assists and 115 points. The Blues and fans believed they had found their dynamic duo for the next decade, but after Oates demanded a pay raise and the team refused to give it to him, the team shipped him to the Boston Bruins halfway through his third season in St. Louis a month out from the trade deadline.
The Blues traded Oates to the Bruins for Craig Janney and Stephane Quintal. Janney, a former 13th overall pick, was very productive in his three-and-a-half seasons in St. Louis, averaging over a point per game as a Blue before being traded to San Jose in 1995. Quintal, a former 14th overall pick, was not very productive in his two seasons in St. Louis before getting traded to the Winnipeg Jets for Phil Housley. Oates played for over a decade after leaving St. Louis and had a Hall of Fame career.
He set career highs in goals, assists, and points in the 1992-93 season with the Bruins, posting 45 goals and 97 assists for 142 points. The trade is one of the biggest what-ifs in Blues' history. Who knows what Hull and Oates could have achieved if they had remained together for the rest of their careers?
3. Ben Bishop

In the 2011-12 NHL season, the St. Louis Blues had a pretty loaded goaltending situation with established starters and young up-and-comers trying to break into the league. The team was riding with a goaltending tandem of Jaroslav Halak and Brian Elliott, which went on to win the William M. Jennings for the fewest goals allowed in the season.
To go along with the tandem, the team had Jake Allen, Ben Bishop, and a newly drafted pretty unknown goalie, Jordan Binnington, in their system, all competing to try and eventually make the NHL. The two goalies most ready to make the jump to the NHL were Allen and Bishop. The team ultimately chose to ride with Allen and trade Bishop.
A day before the trade deadline, the Blues traded Bishop to the Ottawa Senators for a 2nd round pick in 2013. The Blues took Tommy Vannelli with that pick and never ended up playing a game in the NHL. Bishop never received a genuine opportunity in Ottawa and was later traded to Tampa Bay, where he finally broke out as one of the better goalies in the league. Bishop finished top-3 in Vezina voting three times in his career.
Blues fans remember his performance in the 2019 Stanley Cup run against the Blues, where he put up 52 saves in a loss. While Allen has had a long NHL career, his peak never reached the levels of Bishop. Who knows what the Blues could have done with Bishop, but if he did stay, maybe Binnington would not get his chance to break out. We will never know.