The NFL scouting combine begins Tuesday in Indianapolis with approximately 250 draft-eligible players invited for the league's franchises to observe and evaluate at close range. That's not a random number. A total of 253 players were taken in the 2016 draft, including supplemental picks, so the idea is to have very nearly every likely draft prospect on hand for inspection.

Most of the outside attention, naturally, will go to the players expected to be taken on the first day of the three-day draft extravaganza to be held April 27-29 along the Ben Franklin Parkway, an event that should do wonders for traffic. It will be sort of like Made in America, but with Roger Goodell instead of Rihanna.

Everyone can make a decent guess, even now, as to which 32 players will climb the red-carpeted steps to the outdoor stage in front of the Art Museum on Thursday, but the real guts of team building is what takes place on Friday and Saturday.

While attention is lavished on guys like Myles Garrett and Marshon Lattimore, the princes at the top of the board who will show up just to shake hands, the scouts and personnel bosses will be sweating as they sort among the frogs, trying to figure out which fifth-round linebacker has a chance to be something.

The Eagles will be sweating as much or more than the others, because much of their plan for this offseason depends on a high percentage of correct calls with their eight picks in the draft. They have a significant number of holes to fill. Maybe one can be reliably filled with their first-round pick, either the 14th or 15th, pending a coin flip this week with Indianapolis. The others, as well as they might be filled for the coming season, will depend on free agents and the selections made on the second and third days.

Because they are cap-strapped at the moment, the Eagles will also need to create more holes than already exist in order to create room to make significant free-agent additions. If they put $16.7 million in the bank by releasing or trading Connor Barwin, Ryan Mathews, and Mychal Kendrick, considered a likely option, then those gaps will have to be filled somehow.

When Nolan Carroll and Bennie Logan are allowed to walk away as unrestricted free agents, someone will need to occupy those lockers. Leodis McKelvin was already released - the lone deletion in a surprisingly quiet postseason to date - and some other lesser lights figure to follow, mostly a free agent list that could include Najee Goode, Steve Tulloch, Bryan Braman, and Stefen Wisniewski. All understandable moves, all the sort of thing that happens every year, but all represent those empty lockers that have to be taken by somebody.

These are challenges faced around the NFL, but not every team has the double whammy of considerable needs and not much spending room. So, history tells us that the team's potential improvement in 2017 and its timetable for true competitiveness will be determined not by the obvious moves, but by the lesser-noticed decisions about who comes in and who goes out the door.

The latter part - who goes out - is just as vital. The Eagles were right to move past DeMeco Ryans when they did, and Brandon Boykin, as it turned out, and a longer list that also includes Riley Cooper, Bradley Fletcher, Cary Williams, and Jason Avant. But you will only need to study the Super Bowl rings of Patrick Chung and Eric Rowe to know that what came in the door after them was no better than what went out.

Depending on one's point of view, a case could be made for having kept, at one time or another, Evan Mathis, DeSean Jackson, LeSean McCoy, Jeremy Maclin, DeMarco Murray, and, heaven help us, Byron Maxwell. No moves are made in a vacuum. Some of the decisions were because of contracts or as small parts of larger deals. No matter, they were made and, to some extent, the Eagles missed them.

If the Eagles are going to get moving quickly in the right direction, they have to make sure they aren't sending good players out the door this time for the sake of expediency. And they have to hit on the incoming free agents and, especially, on those draft picks from the second and third days. Recently, the haul has been skimpy. Jordan Matthews and Jordan Hicks were second-day selections, as was Isaac Seumalo. (And Rowe.) Jalen Mills and Beau Allen arrived on the third day. If you want to throw in Wendell Smallwood and Halpouliovaati Vaitai as third-day finds, go ahead. It's not a long list, however.

Getting better isn't really a science. There's a lot of luck involved. Starting Tuesday in Indianapolis, the NFL's personnel departments will try to remove as much of that from the equation as possible. First-round picks aren't the problem. Everyone in the draft room will want to take ownership of that call. Later on, however, when the festival on the Parkway has become a dreary march toward Saturday night, there will be those two linebackers on the board and they will look exactly alike and one of them will turn out to be a starter and the other a bust. Every eye will turn to the scouts and coaches who monitored that final exam at the combine.

In the NFL, those are the moments when championships are really won - after almost everyone has stopped watching. The Eagles have a lot of such moments between them and a championship, and the preparation that takes place in the next week will have a lot to say about just how many that might be.