The Toronto Blue Jays are finding out just how quickly momentum can shift in baseball. After last season's Cinderella run that took them all the way to extra innings of Game 7 in the World Series, the team has hit a rough patch that has their manager sending a clear message to one of their key substitutes.

Coming off their best season in the American League, the Blue Jays loaded up with win-now veterans in what looked like a championship-caliber roster. But baseball has a way of humbling even the best-laid plans. This season, Toronto has posted a losing record, and the culprit is one they didn't see coming.

The offense, which carried them through last year's postseason magic, has gone cold. As Rob Langley of the Toronto Sun noted after the team was swept by the Tampa Bay Rays, "An offence that has been benign far too often this season was particularly meek under the bright new roof of the Trop. Facing the stellar Rays pitching, Toronto hitters managed just four runs in three games."

While injuries have certainly played a role—most notably the fractured thumb that sidelined reigning All-Star catcher Alejandro Kirk—manager John Schneider isn't making excuses. The spotlight has turned to the backup catchers, Tyler Heineman and Brandon Valenzuela, who have struggled to fill Kirk's shoes.

Valenzuela, in particular, has had a week to forget. "Saying it has not been a good week for the Toronto backstops is an understatement," Langley added. "In Florida, it was young Brandon Valenzuela who showed his greenness by burning both ABS challenges far too early and later in the game getting thrown out at second with an inexcusable blunder on the basepaths."

For a team built to win now, these are the kind of mistakes that can't be overlooked. Schneider's warning is clear: the Blue Jays need their depth players to step up, or the team's championship aspirations could slip away faster than a wild pitch.