Advanced metrics are a whole other world for most baseball fans, but these days baseball teams don't operate without them.
Now, the new numbers aren't perfect, as many of formulas have been tweaked and tweaked against based on a new concept or improvements in technology.
Many times the metrics don't correlate with the stats found on baseball cards. For every set of probabilities, there's the flip side that says, well, just because it's probable it doesn't necessarily mean it will happen.
How do the math guys often account for that? Luck, good or bad.