This season has not gone the way anyone thought it would for the St. Louis Cardinals in the best way possible.After trading away Sonny Gray, Willson Contreras, Nolan Arenado and Brendan Donovan this offseason, St. Louis looked prepared for a full-scale rebuild. Surprisingly, the Cardinals are only three games out of the playoffs with a 48-44 record, as young players like Jordan Walker and JJ Wetherholt have taken massive steps forward in their development. Wetherholt has impressed so much in his rookie season that St. Louis reportedly agreed to a nine-year extension with the young infielder.The Cardinals need to be cautious about trading for a pitcherMar 6, 2019; Tampa, FL, USA; St. Louis Cardinals hat and gloves lay in the dugout at George M. Steinbrenner Field. Mandatory Credit: Kim Klement-USA TODAY Sports | IMAGN IMAGES via Reuters ConnectDespite the Cardinals' success this season, they need to be cautious about how they handle the upcoming trade deadline. St. Louis' record has left them in an odd position where the team now has to decide whether to be buyers or sellers at the trade deadline. The Cardinals could look to bolster their starting rotation, but so will plenty of other teams, which could drive up the asking prices for any deadline deals."Of the 18 clubs with a rotation ERA higher than league average, 12 are part of that 24-team playoff picture, meaning that a number of teams that could be buyers in the coming weeks will be on the hunt for a starting pitcher or two (or perhaps three?)," MLB.com's Mark Feinsand wrote on Friday. "A handful of surprise contenders (Nationals, Cardinals, Marlins) could look to bolster their respective staffs if they hope to punch a ticket to October. "Truth be told, you can make a legitimate argument for every potential buyer to be in the market for a starting pitcher, which is why the sellers with arms to move are likely to receive healthy returns when all is said and done. It’s a simple case of supply and demand."Despite the Cardinals surprisingly remaining in the playoff picture this season, trading for a starting pitcher at the deadline is not the best move for them. With so many teams looking to improve their starting rotations, pitchers will be sold at a premium at the trade deadline. The Cardinals were ready to spend this season rebuilding, and though they have had a great season, they should not overpay or trade away top prospects, which would hurt their future outlook. If St. Louis decides to add at the deadline, the team should prioritize buy-low targets or players on expiring deals that won't impact the team's flexibility moving forward. More MLB: JJ Wetherholt Becomes Highest-Paid Cardinals Player With $112M Reported ExtensionAdd us as a preferred source on GoogleFollow