After three long offseasons of persisting trade rumors, the question has to be asked: Why would Upton veto a trade that would have finally sent him out of town?

1. Rain

On average, Seattle has more than 150 days of precipitation per year. The Emerald city also averages 35.9 inches of rain per year. Phoenix by comparison has less than a month of precipitation days per year and 7.8 inches of rain.

2. Safeco Field

Without question, Safeco Field is a beautiful place to take in a ball game. With that said, the 54,000-seat stadium is by no means a hitter's park. According to ESPN.com, since the stadium opened in 2000, the Mariners have scored the fewest runs and have the worst batting average of any American League team during that span.

In 2012, Safeco Field averaged just 1.43 home runs per game. By comparison, Chase Field had 2.15 fly out of the yard per game (58 more over the course of the season).

3. Home/road splits

During his five-year MLB career, Upton has taken full advantage of Chase Field's hitter-friendly dimensions.

Over the past three seasons, Upton has batted .253 with 26 home runs and 93 RBI away from Chase field. However at home, the former No. 1 overall pick is considerably better, batting .311 with 39 home runs and 131 RBI. His OPS is also .189 higher in games played in the Valley.

And there's this reason, provided by Arizona Sports 620's Paul Calvisi on Friday:

Would a player veto a trade to SEA because he's building a house? Sources tell me Justin Upton is in middle of building a dream house in PV

— Paul Calvisi (@PaulCalvisi) January 12, 2013

Either way, Upton remains a D-back for now. Whether that's still true heading into spring training, well, that remains to be seen.