PITTSFORD — Buffalo Bills second-round pick James Hardy became the third and most significant rookie to sign with the team Thursday, the day before training camp opens in suburban Rochester.

Besides Hardy, a receiver who was selected 41st overall out of Indiana, the Bills also signed third-round pick, defensive end Chris Ellis, and sixth-round pick, running back Xavier Omon, both to four-year contracts. That leaves Buffalo first-round pick Leodis McKelvin, a cornerback, as the one unsigned player before the team’s first practice Friday morning.

The Bills were negotiating with McKelvin late Thursday evening. Earlier in the day, Bills chief operating officer Russ Brandon expressed confidence that the first-round pick would be signed in time for the start of camp.

Hardy has the chance to make an immediate impact on what had been a popgun offense. The Bills are counting on the 6-foot-5 receiver to compete for the No. 2 spot to take the pressure off starter Lee Evans this season. Hardy is the tallest receiver ever drafted by the Bills, and provides their offense a tall and speedy target it has lacked since trading Eric Moulds to Houston prior to the 2006 season.

Hardy finished his college career with 191 catches for 2,740 yards and 36 touchdowns in 36 games, including 26 starts. As a senior he had a school record 79 receptions for 1,125 yards and 16 touchdowns.

Ellis, selected 72nd overall out of Virginia Tech, was an all-Atlantic Coast Conference defensive end last season. He had 8 1/2 sacks as a senior and 22 for his career.

His contract includes $800,000 that’s guaranteed and is potentially worth $3.2 million if he meets all incentive clauses.

Ellis is expected to compete for a backup spot behind starters Aaron Schobel and Chris Kelsay and on a revamped defensive line that will be anchored by newly acquired tackle Marcus Stroud.

Omon, selected 179th out of Division II Northwest Missouri, became only the second college player to have 1,500 yards rushing in each of his four seasons. He finished with 7,073 yards rushing and scored 98 touchdowns.

Omon is expected to compete with Dwayne Wright for the third-string job behind starter Marshawn Lynch and backup Fred Jackson.