Eagles fans booed their team off the field at halftime of Sunday night's loss to the Cowboys, approximately nine months after many of the men receiving the boos delivered the boo-ers the greatest sporting thrill of their lifetimes.

I have never understood this, personally. Even when I was a rooting fan with a vested interest in the successes and failures of specific teams, I never agreed with the idea of booing the team you love for poor play. For lack of effort, maybe, or for some kind of classless on-field behavior. But for playing poorly or losing? Why? It's not as if they don't realize they're losing and your booing will alert them to the fact. It's not as if you want them to win more than they want to win themselves. Booing your own team always strikes me as kind of antithetical to the fan experience. And, yes, I find it even more puzzling when you're booing the people who won your team its first and only Super Bowl.

But understand: This isn't a lecture. It's just the way I feel. I've heard the counterarguments, and I understand that a lot of fans consider this a fundamental right of fandom: the right (obligation?) to show displeasure when your team disappoints. I'm not saying I'm right and those who boo are wrong -- just that it never made a lot of sense in my own head, where I acknowledge a lot of things don't make sense.

Regardless of where you land on this, we can agree that the booing Sunday night in Philadelphia was the result of deep disappointment. That's why it was the inspiration for this week's column, which takes a look at the three most disappointing teams of the 2018 NFL season so far. We begin with the defending Super Bowl champs.

This year's Eagles weren't supposed to be 4-5 and losing to the Cowboys in Week 10. They were supposed to be the team that bucked all of the daunting recent history, repeating not only as NFC East champions but maybe also as Super Bowl champions. They won the thing, after all, without their starting quarterback and left tackle. They had every reason to believe they could be even better this season.

They are not. They're tied for second with Dallas, two games behind first-place Washington in the division. They're a middle-of-the-pack team on offense and on defense. Their secondary is shredded by injuries, and they haven't been able to put games away with their pass rush in the fourth quarter the way they did last season. Statistically, it's tough to find too many stark differences between where the Eagles were last year and where they are this year. But when you look at plays that make the difference in close games over a long season, it's easier to spot.

Last year, the Eagles were second in the league (behind the Bills, somehow) in third-down conversions and first in fourth-down conversions. This year, they're 11th in third-down conversions and tied for fourth (with five other teams) in fourth-down conversions. Last year, they ranked first in red zone efficiency, converting 65.5 percent of their red zone drives into touchdowns. This year, they're 17th in that category, at 55.9 percent. In the fourth quarter and overtime this year, the Eagles are converting 34.4 percent of their third downs, which ranks 20th in the league. Last year, that number was 40.3, tied for eighth.

The Eagles aren't a bad team, but they've lost a little bit of last year's ability to make the exceptional play at the critical time. That makes them more like the rest of the teams in the league, but they have time to turn it around and two games left against Washington to help them make up the deficit. As with the other two teams on our list, it isn't yet over for Philly. The Eagles just need to start looking more like the 2017 version of themselves if they're going to make a repeat run.