The St. Louis Cardinals have built their roster to be sellers at the trade deadline, but they are currently playing pretty solid baseball. They entered Wednesday's action just 2 1/2 games behind the Chicago Cubs for the top spot in the National League Central. The Cardinals have plenty of players on expiring contracts that could be trade chips at the deadline, and that includes right-hander Dustin May , who has turned things around after two rough starts to begin the season. However, former Cardinals' pitcher Kyle Gibson gave his take on the matter, and said that the Cardinals should think twice before trading May. "I think if Dustin May is throwing the ball so well that he is one of the more sought-after starters on the market then I think that's probably a reason why your team is in playoff contention," Gibson said. "I think if there's one area that is really going to hurt this team down the stretch, it's going to be losing Dustin May and losing a starter.…