The St. Louis Cardinals have far exceeded expectations this season, but that doesn't mean that the team needs to make any rash decisions moving forward. Heading into this season, the Cardinals were not expected to be successful. St. Louis began last season the same way it did this year, with a 50-45 record through 95 games, but sold at the trade deadline after a second-half falloff. The Cardinals further dove into a rebuild this offseason after trading Nolan Arenado, Brendan Donovan, Sonny Gray and Willson Contreras. History seems to be repeating itself as the Cardinals have lost six of their last eight games since the All-Star break. They are a little over two games out of the last playoff wild-card spot. Though the upcoming trade deadline offers St. Louis a perfect opportunity to improve its roster, the team needs to be cautious about the future. St. Louis should not consider rentals at the trade deadlineSep 17, 2018; Atlanta, GA, USA; Detailed view of a St. Louis Cardinals hat and glove in the dugout against the Atlanta Braves in the first inning at SunTrust Park. Mandatory Credit: Brett Davis-USA TODAY Sports | USA TODAY SportsThe Cardinals were prepared for a rebuilding year and shouldn't let their current success lead them to make rash decisions. If they do wind up buying at the trade deadline, their top priority should be to upgrade their lineup "within reason" with players that are under team control beyond this season without giving up valuable prospects. "Top Priority: Upgrade the lineup within reason. St. Louis probably won't do much of anything about the deadline," Bleacher Report's Kerry Miller wrote on Friday. "The Cardinals only have a couple of impending free agents, two of whom (JoJo Romero and Ramón Urías) are on the IL anyway. "And after unloading Sonny Gray, Nolan Arenado, Willson Contreras and Brendan Donovan this past winter in the name of shedding payroll, getting younger and restocking the farm system, it'd be a bit nonsensical to now trade away a decent chunk of said farm in pursuit of what is maybe a 30 percent chance at a wild card spot. However, if they can get a buy-low bat that is controllable beyond this season, that's worth exploring."St. Louis' emphasis on development this season has paid off tremendously. Jordan Walker, Iván Herrera and Riley O'Brien were all named All-Stars for the first time, and JJ Wetherholt earned a massive nine-figure extension after impressing in his rookie season. The Cardinals sacrificed a lot this offseason to restock their farm system and reset their roster. After going through all of that effort, it wouldn't make sense for the team to acquire a short-term rental at the trade deadline. Instead, perhaps the team should pursue players like Jake McCarthy or Carlos Cortes. More MLB: When Will Cardinals Promote Impressive 25-Year-Old Pitching Prospect?Add us as a preferred source on GoogleFollow