For the incoming draft class, though, it's our first chance to see how they are integrating at the next level. Which rookies are leaving the biggest impression on coaches, teammates and beat writers? Here's a sample of nine first-year players standing out from the pack.
DeAndre Hopkins, Houston Texans wide receiver
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Under general manager Rick Smith and coach Gary Kubiak, the Texans habitually have dispensed the notion of competition when it comes to first-round picks. They are drafted to be thrown into the fire as immediate contributors. Kubiak's praise for Hopkins already has run the gamut from "extremely special" to "obviously very gifted" and "very competitive."
Johnathan Cyprien, Jacksonville Jaguars safety
Manti Te'o, San Diego Chargers, linebacker
The Chargers have done a commendable job of sweeping Te'o's fake-girlfriend scandal under the rug. All of the talk out of offseason practices was about Te'o's on-field impact. The former Notre Dame star appears to be one of those rare NFL-ready rookies with instincts who just "gets it." Te'o might not be a three-down linebacker, but he's going to start from Day 1.
D.J. Swearinger, Houston Texans safety
Tyler Eifert, Cincinnati Bengals tight end
Matt Elam, Baltimore Ravens safety
The last pick in the first round is impressing teammates as a quick study who always is around the ball. "He's tough, he's fast, he gets football," secondary coach Teryl Austin said, "and I think he is going to be a fine player for us soon."
Elam already is playing in both base and nickel packages. "That's pretty impressive," veteran cornerback Corey Graham explained. "You don't see that much, especially in the first couple of months of being on the team."
Sio Moore, Oakland Raiders linebacker
"I like Sio," Allen said last week. "He's a big, powerful man. And he's got a little bit of pass-rush ability to him. So, I like some of the flexibility that he gives us. His work ethic and his understanding of the game of football is what's going to allow him to be a good player for us."
Tyrann Mathieu, Arizona Cardinals safety
As expected, the man formerly known as Honey Badger was "buzzing around plays" as an immediate starter in nickel packages during OTAs. "He gets things the first time the coaches tell it to him," head coach Bruce Arians said. "He's got natural instincts to play football. I'm really happy for him. He's playing really well."
Vance McDonald, San Francisco 49ers tight end
McDonald "may have been the biggest standout" this offseason among the 49ers' rookies, according to the Sacramento Bee. The No. 55 overall pick was a favorite target of all the quarterbacks and showed a knack for making difficult catches. He's expected to fill Delanie Walker's role as the No. 2 tight end, complementing Vernon Davis.