BALTIMORE - Doug Pederson has spoken often, and did so again after the Eagles' 27-26 loss to the Ravens here Sunday, of the lessons that his youngest, greenest players have been learning throughout this season. And so it was that, with 16 seconds left in the first half, Steve Smith Sr. took Jalen Mills to school.

A 22-year-old rookie cornerback, a seventh-round draft pick, Mills lined up across from Smith, who is 37 and has 1,021 receptions and has seen his share of rookie cornerbacks in his 16 years in the NFL. Smith ran a go route, and when Mills shifted his hips and moved to the outside, Smith cut inside and zoomed past him, widened the route to keep safety Jalen Watkins at a comfortable distance, and caught a perfect pass from Joe Flacco for a 34-yard score.

"Touchdown, bro," Mills said. "I ain't giving nothing else on it."

There wasn't much else for Mills to say. Getting burned for a touchdown by the likes of Steve Smith Sr. is a rite for passage for just about any defensive back, and make no mistake: The Eagles are all about rites of passage and growth and development now. If there were always doubts about when exactly the franchise decided that 2016 was a rebuilding season - after signing Sam Bradford but before trading up to get Carson Wentz or maybe right when they traded Bradford but maybe not because they started 3-0 or maybe later when they lost in Seattle but arguably not for real until Pederson spoke after the Packers loss about looking ahead to next season - those doubts are gone.

"These are valuable lessons going forward," Pederson said, as if a cue card were in front of him. "We continue to learn from this as a team and as individuals."

In that context, the details of what happened Sunday at M&T Stadium - as thrilling and, for the Eagles, unfulfilling as the finish was - are less material than the pragmatic function that the game served. While it would be nice for the Eagles to win one or both of their two final games, against the Giants and the Cowboys, it would be more beneficial if they started to learn whether they have young, inexperienced players worth keeping and who those players might be.

It's not that easy a task. Look at the Eagles' roster and how these 14 games have played out. It's a challenge to find any players who weren't already presumed to be part of the Eagles' future who have established themselves as lynchpins for 2017 and beyond.

Remember: The Eagles already have bet heavily that they've found the core of their team, locking up Zach Ertz, Malcolm Jenkins, Vinny Curry, Lane Johnson, Brandon Brooks, Rodney McLeod. And if Wentz hadn't played a snap this season, he still would enter next season with the expectation that he is supposed to be a franchise quarterback. For all his first-year struggles, he has done more than enough to suggest that he is the least of the Eagles' problems. His talent and potential are less mysterious now. "He's going to be here however long he wants to be here," tight end Trey Burton said.

But the Eagles are still 5-9 and have lost five straight games, and who among their unknowns has established himself as indispensable? Who took a great leap forward this season? Who did the coaching staff develop? Middle linebacker Jordan Hicks was a playmaker as a rookie and has been solid again this season. Jordan Matthews is productive, smart, and a good teammate - all the things he was during his first two seasons here. Neither emerged as a dominant force at his position.

Nelson Agholor has offered little evidence that he can or will justify being a first-round pick. Halapoulivaati Vaitai, after his inauspicious debut against the Redskins, looked a bit better before suffering an MCL sprain. Isaac Seumalo held his own at right tackle Sunday and is a natural guard, but he has started three games, just three. Are those two surefire starters on an above-average offensive line?

Mills has loads of aggression and self-confidence, and he is forever undaunted in his post-incompletion finger wags, but can the Eagles pencil him in at one of their cornerback spots next season? Will Wendell Smallwood and Byron Marshall be the starting backfield? There was an Eagles running back who racked up 128 yards on 20 carries Sunday, but everyone already knew that Ryan Mathews, when healthy, runs hard and powerfully. The true revelation was that Marshall, in his first action of the season, used a nifty jump-cut to rip off runs of 12 yards and 10 yards on back-to-back plays in the fourth quarter.

"I don't ever plan on being on the practice squad again," Marshall said. "These last couple of games, I'm just really trying to show them that I belong here - not that I can just kind of play with them, but I can play with them."

If the Eagles are smart, Marshall will get that opportunity against the Giants and the Cowboys. Mills should be out there more against Odell Beckham Jr. and, if the Cowboys play him, Dez Bryant. These promise to be hard lessons, but these are the questions that this franchise has to answer, or start to answer, before training camp opens in July. It's not enough to have high hopes for Wentz and those players whom the Eagles already have decided, for good or bad, will be here for the long term. They have to find new faces for the future, too. That's the point of a rebuilding season, after all. It should be, anyway.

@MikeSielski