People say they understand that sports is a business. Most people don't really mean it. Most people want to buy the jerseys and watch the highlights and feel a kinship with the athletes and coaches and personalities, and they want every once in a while to reach into the pot of gold at the rainbow's end, lift their hands out, and savor the sensation of the coins falling through their fingers. They give their loyalty, and they want their loyalty reciprocated. They want to connect. They want to come along for the ride.

All of that is especially true here, in Philadelphia, because sports is a fundamental aspect of the region's culture. Our civic self-esteem is tied to sports, to the four major professional teams in particular. When someone says you can walk around the city or one of its suburban neighborhoods on an autumn or winter Monday and know, just from the faces and demeanors of the passersby, whether the Eagles won or lost the day before, those faces and demeanors are a reflection of that shared identity.

Sports is the thing that brings many of us together. In that way, it is much like a religion - not as important, of course, but similar in that it is ever-present and intrinsic to who we are.

It is like a religion in another way, too: There are supposed to be answers there, and answers are comforting and reassuring. That's why what Chip Kelly and the Eagles did Tuesday - releasing Cary Williams and Trent Cole, reportedly agreeing to trade LeSean McCoy to the Buffalo Bills for linebacker Kiko Alonso - is at once surprising and thrilling and terrifying to anyone who bleeds green.

It's why, to a lesser extent, the ceaseless reshaping of the 76ers' roster over Sam Hinkie's first two seasons as general manager has generated so much hullabaloo, and it's why there's so much curiosity over what kind of the team the Flyers might become, now that Ron Hextall has begun following through on his promise of a patient, lengthy rebuilding process.

But none of those narratives has any discernible or predictable ending yet, and when it comes to sports and especially the Eagles, Philadelphia is not a town that embraces uncertainty. So each of the Eagles' three moves Tuesday came with its own communal reaction.

Cary Williams? Guy couldn't cover all that well and wasn't worth the money anyway. . . . Trent Cole? Shame. Guy was a warrior here for a long time, but he was due to make a ton under the salary cap. It was time to say goodbye, I guess. . . . LeSean McCoy? REALLY? Shady? And what the heck is Chip going to do now?

It's true everywhere that fans will have an affection for athletes who have excelled for a particular team for a lengthy period of time, and McCoy over his six seasons with the Eagles developed into one of the best running backs in franchise history. So it's easy to get caught up in the shock of his departure - at age 26, presumably still in his prime - and overlook a few key factors that almost certainly played into Kelly's decision.

McCoy will count $12 million against the salary cap this season, a high number at a position whose value around the NFL is decreasing because capable running backs are fungible. He also ranked 15th out of 18 eligible running backs last season in Pro Football Focus's "elusive rating," an attempt to measure how many of a tailback's yards are due to him and how many to his blockers.

Put simply, McCoy didn't break tackles or make people miss like he used to, and possessing those traits is a prerequisite for a running back in Kelly's offense. A lot of Eagles fans think of McCoy as he was or is. In a salary-cap league of abbreviated playing careers and non-guaranteed contracts, though, Kelly has to think of McCoy as he will be.

And maybe Kelly will be wrong about McCoy and about Alonso - the 2013 Pro Football Writers defensive rookie of the year, a player who missed the entire 2014 season because of a torn ACL, a kid who played for Kelly at Oregon.

Maybe this entire purging of the 2014 Eagles will lead to a 2015 roster loaded with former Eugene residents and blow up in Kelly's face. That's the default, sky-is-falling reaction around here. But the Eagles, despite their 10-6 record, were not a Super Bowl-caliber team last season, and Kelly now has an ungodly amount of salary-cap space to work with, and no one yet has a true and clear sense of how he'll use it.

The answers are open-ended at the moment. Sports is a business, and as Hinkie said just after the NBA trade deadline, "it will require us to make tough decisions and be comfortable with uncertainty." He meant it. It's obvious Chip Kelly does, too.

@MikeSielski