You sat inside the press box at CenturyLink Field on Sunday and watched with a perverse combination of curiosity and horror and pity as the Eagles lost to the Seahawks, and you wondered: Who was the last Philadelphia athlete to be as mentally lost as Nelson Agholor now is? Ilya Bryzgalov? Domonic Brown? Nnamdi Asomugha? Did they sink this low? When Joe Cowley forgot how to throw strikes for the 1987 Phillies, was it as excruciating to sit through his five appearances then as it is to see Agholor make the kinds of fundamental mistakes that a Pop Warner coach couldn't forgive?

From his inability to line up properly on that nullified Zach Ertz touchdown to that Carson Wentz pass that caromed off his elbow four plays later Sunday, from his failure to produce at a level befitting a first-round pick to that late-night locker-room rant in Texas after an overtime loss to the Cowboys, Agholor has been a source of frustration all season. But if he's to have any hope of salvaging his career with the Eagles, and maybe in the NFL, it's important to understand why he's reached the point that coach Doug Pederson might bench him. It's important to understand why Yo Murphy - the former NFL wide receiver who has been Agholor's trainer and confidant for nine years now - has spent the last two days dying inside, knowing the torture that Agholor has likely been putting himself through.

"Every little thing with Nelly now is just magnified," Murphy said in a telephone interview Tuesday from his training facility in Tampa. "When a guy's a thinker like he is, he can think things are worse than they are. . . . He's never, ever, ever taken a day off. He works. He works. He works. He works. It's just a tough thing. It breaks my heart because I know the guy he is, and he's not a guy who slouches and takes plays off."

It would be easier for everyone - Agholor, Pederson, the Eagles, their fans - if he were that kind of guy. People could boo him, the front office could absorb the salary-cap hit and cut him, and everyone could maintain a clear conscience. But this isn't about a player with a questionable work ethic or a sense of entitlement getting some comeuppance for correctable flaws that he can't be bothered to fix. Agholor wouldn't have stood at his locker after Sunday's game for as long as he did, laying himself bare, speaking in depth about being trapped inside his own head, if he didn't care.

Look at that pass he didn't catch Sunday. He ran a terrific route against Richard Sherman, one of the NFL's best cornerbacks - a deep curl to the middle of the field that left him wide open. Yet you could almost see him thinking, Justcatchtheballjustcatchtheballjustcatchtheball as Wentz's throw arrowed toward him. He dropped the ball because he's holding on too tight. We see this sometimes. A golfer gets the putting yips. A second baseman double-clutches on every throw to first. A goaltender fights the puck. It's the most excruciating thing to witness in sports, because we think of these athletes as self-assured and indestructible, and suddenly there they are in front of us, so fragile, so helpless, paralyzed by their own public insecurity.

All the anger and outrage over Agholor's struggles won't motivate and inspire him. If anything, those reactions could further crush his confidence, if that's even possible, because recovering from this sort of psychological setback isn't the same thing as rehabilitating a torn knee ligament or waiting for a broken bone to heal.

"It's probably worse," said Murphy, who spent three seasons in the NFL with four teams. "The physical, that thing that you can feel and touch, is easier to cope with. The doc says, 'We're going to do this surgery, and in eight months, you're going to be fine.' When you have that ACL and say, 'OK, four more months. Here's what I've got to do. This is the outcome I'm going to get,' it's easier than saying, 'I still run fast. I'm still a good athlete. I can do the things I've always done. What's going on?' That's the thing about it. It's that unknown."

Agholor despises the unknown, and that hatred is practically woven into the double helix of his DNA. His family emigrated from Nigeria when he was 5. His father was a janitor at the University of South Florida. His mother worked at a nursing home. For a 23-year-old man with that background, with that ethos, another hour on the JUGS machine won't accomplish anything. "I don't know that he ever dropped a ball in practice for us," said Dominick Ciao, Agholor's high school coach at Berkeley Prep in Tampa. He is so meticulous that, after the Eagles drafted him in 2015, he talked with the team nutritionist, determined the optimal amount of time to allow himself to digest his breakfast, and scheduled his morning workouts with Murphy accordingly.

When he's playing well, that diligence and preparation give him an edge. But his lack of success since entering the NFL - he has just 50 catches and two touchdowns in 23 games - seems to be preying on his mind, and now he's akin to a machine with a single defective part that has caused the entire apparatus to break down.

"Nelly's not a guy who has fun with football," Murphy said. "There are some guys who do. They run around and have a good time. Nelly is ultra-focused and locked in, so when you get someone like that, he's just got to lock back in to the right things. He's locked into having conversations about dropping balls instead of locked into, 'OK, I know this team is in Cover-3. Here's where I've got to be, and when the ball comes, attack and go.'

"It's focus. I just want him to recall who he is."

So how does he remember? This is a difficult, touchy situation for Pederson to handle. Can he afford to keep Agholor in the lineup when the kid is fighting every football thrown his way? Is keeping Agholor on the sideline and letting him stew in his own self-doubt really the solution? The truth is that Nelson Agholor might be on his own inside himself, and for the sake of his future with the Eagles, he had better find a way out.

@MikeSielski