Even as they ride their longest winning streak in more than two years, the Chicago Cubs are their own worst enemy. Case in point: Cubs rightfielder Tyler Colvin is in stable condition at a Miami hospital after he was hit in the upper chest by a piece of a maple bat during Sunday’s game against the Florida Marlins. The bat shattered as catcher Welington Castillo smacked a double, while Colvin was running down the third-base line when a portion of the bat punctured his chest. A portion of the bat hit Colvin in the upper right side of the chest. Colvin is being treated with a chest tube to prevent a collapsed lung. Colvin, who is expected to miss the rest of the season, hit .254 with 20 homers and 56 RBIs in his first year in the majors. Incidentially, Colvin did manage to score from third. The Cubs need more troopers like Tyler.