WASHINGTON -- Bryce Harper calls it the Sun Monster.

We were reminded Monday that it doesn't play favorites. But we were also reminded that it could be preparing for its first big appearance on the national stage.

The Nationals are about to make their first playoff appearance. But so, it seems, is the Sun Monster.

What is it?

Well, it's really just the sun. But it's the way the sun appears during certain games at Nationals Park, and the way that it keeps outfielders from seeing fly balls.

The Nationals lost to the Brewers Sunday in part because Harper (in center field) and Jayson Werth (in right field) completely lost balls in the sun, leading to at least two Brewers runs. Monday, the sun turned a Werth fly ball into a double when Carlos Gomez couldn't find it, leading to the final five runs that scored in the Nationals' six-run fourth inning.

Nationals Park has been open since 2008. Why are we just hearing about this now?

Simple. It's only bad at certain times of year.

"Time of year affects the degree of difficulty," Nationals general manager Mike Rizzo said Monday morning. "Early spring and late fall is when it's worst."

There you go. We never really paid attention to Nationals games in early spring. Until this year, we never cared about the Nationals in late fall.

Now we do. Now there will be playoff games at Nationals Park next month. There's every chance that there will be day playoff games, or late-afternoon playoff games.

There's every chance there will be more fly balls lost in the sun.

"During day games, it'll be a tough sun field," Rizzo said. "But it'll be tough for both teams."

The Sun Monster doesn't play favorites.