The Philadelphia Eagles are planning a $125 million renovation of Lincoln Financial Field. That in itself is unremarkable. As Seattleites well know, an enormous amount of money is spent building and renovating professional sports facilities all the time.

But I did find two details kinda interesting. First, the renovation comes only ten years after the stadium was built at a cost of $512 million ($256 million shouldered by taxpayers). And that's on top of millions of dollars of routine maintenance and a previously announced $30 million green energy initiative.

Second: "No public funds are being used for this renovation, according to the team."

The obvious lesson to learn from this is that team owners really do see an economic imperative in frequently updating their facilities—even facilities as new as ten-year-old Lincoln Financial Field. Of course, they'd rather make taxpayers pick up the tab, but clearly, the Eagles wouldn't be making a $125 million investment if they didn't think they would realize a healthy return.

The average useful economic life of a professional sports facility may seem ridiculously short, but that is the nature the industry. A decade ago, when KeyArena was less than a decade old, the notion of replacing it seemed outrageous. A decade later (and the issue of public financing aside), not so much.