Ronald Darby's first day with the Eagles came Saturday, and he watched practice from the sideline in sweats and a bucket hat. He needed to wait for Jordan Matthews to complete his physical in Buffalo before taking the field for the Eagles.

It's not expected to take long for Darby to become the Eagles' top cornerback. After the Eagles traded Matthews and a third-round pick for Darby on Friday, the 23-year-old Maryland native is in line to be a big part of the Eagles' present and future. He brings top-end speed that the other cornerbacks lack and a playing style that fits what defensive coordinator Jim Schwartz wants at the position."Everybody knows me for my speed," Darby said, "but I'm willing to come up and tackle. Play aggressive."Darby thrived as a rookie in 2015 as an immediate starter for the Bills and had two interceptions and 21 passes defended. He was named Pro Football Focus' defensive rookie of the year that season. His performance declined last year, and Darby said he needed to do a better job finishing plays. Eagles safety Corey Graham, who started next to Darby in Buffalo, said scheme adjustments last season hurt the entire defense. He remembers how Darby excelled as a rookie and said that will translate to the Eagles."He was special the whole year," Graham said. "He was lights out from the beginning. …The kid has talent. As long as he can get in the playbook and learn exactly what we're doing and play fast, he'll be good."Graham, who has played in Schwartz's system before, indicated that Darby is a better fit in the Eagles scheme than what the Bills are expected to run this year with new coach Sean McDermott. Darby's man-to-man coverage ability is expected to be an asset. Darby didn't anticipate it taking a long time to learn the Eagles defense. Although Graham said Darby is better when he can play fast and not think, the concepts are similar to what Darby has done before."Corner, it's not that difficult once you get the concepts down, know the names of the plays," Darby said.Darby said he's a "great match" for the aggressive personality that Schwartz likes in his defensive backs. It's how Darby said he's played since he was at Florida State. In man-to-man defense, he said he can run against anybody.A high school track star who won the bronze medal in the 200 meters in the 2011 World Youth Championships, Darby ran a 4.38-second 40-yard dash at the combine in 2015. If he was tested this summer, he said the time would be even faster."I know for sure low 4.3s," Darby said.Safety Terrence Brooks, who was Darby's teammate at Florida State, said that Darby is "so damn quick, it's crazy." But he also commented on Darby's physicality, which he didn't think should be lost when looking at Darby.Graham and Brooks are among the familiar faces Darby saw at Eagles practice. He knows former Bills teammates Ron Brooks and Nigel Bradham and former Florida State teammate Tim Jernigan. That will help in the transition to the Eagles.Coach Doug Pederson said the Eagles will treat Darby similar to how they did Graham last week - give him a couple days to evaluate how he fits and then figure out what to do. Pederson said the Eagles will "take it slow with him," not wanting to put him on the field when he doesn't know the defense. If Darby is available for Thursday's game against the Bills - Darby's former team - Pederson said he would play.The Eagles need Darby ready by Week 1. That's when the NFC East schedule starts in Washington. Howie Roseman said the Eagles watched how Darby played against the division's receivers in 2015. Asked if he's excited to go against them again, Darby responded, "Hell yeah!"Darby watched the Eagles' other young cornerbacks on the field Saturday. He stood with Sidney Jones. Much is expected of Darby this season, but if the Eagles were right about the trade, he'll be in the Eagles secondary for years to come.He said it's even more "exciting" to know that it will come in Philadelphia in front of fans that impressed him in person when the Bills visited in 2015."The future's looking bright," Darby said. "Right now's looking bright."