But there are exceptions, and Johnson was one last year. The Oklahoma tackle had played only two seasons on the offensive line, and there was some question about his readiness. But he fared well against some of the best pass rushers from the Class of 2013 during Senior Bowl practices.
Johnson followed his performance with a freakish showing at the scouting combine and rocketed into the top 10 on many draft boards, eventually being selected fourth overall by the Eagles in Chip Kelly's first draft.
The Eagles coach, his assistants, and a full contingent of scouts, led by general manager Howie Roseman, are expected to be here this week to narrow the list of prospects who are suited to Kelly's schemes.
"We have to still continue to outline what we're looking for in players because there are certain players that are great fits; there are other players that are tremendous football players but they may not fit scheme-wise into what we're doing," Kelly said earlier this month. "That's not what we're looking for."
But Kelly knows that concessions sometimes have to be made, and the Eagles will have only seven shots - they currently have a draft pick in Rounds 1-4, two in the fifth, and one in the seventh - to get the players they want.
"This isn't recruiting where you can go out and offer and try to get them to come," Kelly said. "There's a selection in the draft process, and we're not going to pick until the 22d [in the first round]. There's 21 other guys that we may covet, but we don't have an opportunity to get them.
"You have ideals, and you have parameters in terms of what we're looking for, but sometimes it may not be exactly what you're looking for. But you make do with it."
Here are some of the seniors the Eagles may have particular interest in this week based on need and Kelly's preferences:
Outside linebackers. Dee Ford is probably the most recognizable name after his standout performances throughout the Southeastern Conference season and in the national championship game. The Auburn star notched 101/2 sacks and likely will project as a 3-4 edge rusher. He isn't very rangy, though (6-foot-2, 240 pounds).
Jeremiah Attaochu (6-3, 242) of Georgia Tech has the type of athleticism pro teams covet even if he isn't as polished as Ford. Louisville's Marcus Smith (6-3, 252) could end up in a 4-3 defense, but he has the ability to drop into coverage. Adrian Hubbard has great size (6-6, 252), but the Alabama star has underperformed. Brigham Young's Kyle Van Noy (6-3, 245) has something to prove as a pass rusher. Telvin Smith (6-3, 218) of Florida State has 4-3 outside linebacker written all over him, but he has added weight and could be a versatile standup rusher.
Safeties. Ahmad Dixon of Baylor (6-0, 205) may be the most physically gifted safety here. He could improve his stock by dominating against a subpar crop of receivers. Washington State's Deone Bucannon, (6-1, 215) is another hitter who can struggle in coverage. Craig Loston (6-2, 209) of Louisiana State has a similar skill-set. Vanderbilt's Kenny Ladler (6-1, 205) was savvy enough to play both safety spots in college. Jimmie Ward (5-11, 192) of Northern Illinois and Terrence Brooks of Florida State (5-11, 200) could be climbers.
Cornerbacks. Utah's Keith McGill is one of several cornerbacks who could be better suited to play safety in the NFL. The Eagles like their outside corners rangy, though, and that describes McGill (6-3, 205). Marqueston Huff (6-0, 195) was Wyoming's leading tackler at the safety spot. Oklahoma's Aaron Colvin (6-0, 192) may be a better fit in the slot. Auburn's Chris Davis (5-11, 200) is best known for his game-winning touchdown return on a missed field goal in the Iron Bowl.
Wide receivers. If the Eagles are looking for bigger, more physical receivers, there are several here. Jordan Matthews (6-3, 206) of Vanderbilt is the only headliner, though. He isn't especially quick but uses his size well and has good hands. Jeff Janis from Division II Saginaw Valley State (6-3, 218) could be an intriguing mid- to late-round pick. Mike Davis (6-2, 195) of Texas, Jared Abbrederis (6-2, 190) of Wisconsin, and Kevin Norwood (6-2, 195) of Alabama are slighter but were reliable ball catchers. Of the smaller receivers, Josh Huff (5-11, 202) could draw the most interest from the Eagles because he played three seasons under Kelly at Oregon.
Quarterbacks. The Eagles aren't likely to draft a quarterback in the first round, but they could pluck one in the later rounds as they did last year when Matt Barkley was selected in the fourth. Derek Carr (6-3, 218) of Fresno State is considered the top thrower here and could end up a first-round pick, but Kelly may have more interest in Tajh Boyd (6-1, 225). The athletic Clemson quarterback could thrive in the right system. Jimmy Garoppolo (6-3, 222) of Eastern Illinois was added after Alabama's A.J. McCarron dropped out and after his impressive showing in the East-West Shrine Bowl. Garoppolo does a little bit of everything. Logan Thomas (6-6, 254) of Virginia Tech and Stephen Morris (6-2, 218) of Miami hurt their stock with rocky senior seasons in which they often made poor decisions.