A team’s fortunes over the course of a six-month season typically hinge on more than one factor, but depending on how critical said factor is, that one wild card can affect things greatly.

It can be a good or bad performance. It can be a health issue, for better or worse. It can be how a player bounces back from an injury or a poor previous season. It can even be how a player produces during the ever-important contract year.

Whatever the case or reason, these are players who can greatly impact their teams, their division races and even World Series chances depending on how they turn. That is why they become important pieces in determining how their league’s landscapes play out.

This year, there is no lack of such examples. Every team has at least a couple of these X-factors, and they have the potential to make or derail an entire season depending on how they break.

For 2015, these are some of the most important variables. Either way they go, they will all have a significant impact on their team’s year.

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