Foxboro, MA (AP)  -- The New England Patriots' seven draft picks and 11 undrafted free agents took to the field Friday for their first rookie minicamp, which coach Bill Belichick stressed was just the start of a long process to make -- and contribute to -- the team.

"We've taken a first step and we're probably running a 26-mile race," Belichick said. "You don't try to call the Boston Marathon after one block, that's what you're really talking about. It's a long way to go."

Belichick watched the action with Scott Pioli, the Patriots' vice president of player personnel. The team also invited nine unsigned players to the minicamp.

"Obviously a lot of new faces and it's always an exciting time of year to work with new kids and see their eagerness and kind of start at a really fundamental level," Pioli said. "It's just the most basic terminology and plays and techniques and all of that."

The Patriots will spend the spring and summer evaluating which players could replace several departed defensive players, including starting cornerback Asante Samuel who signed with Philadelphia. Linebacker Rosevelt Colvin remains an unsigned free agent.

Terrence Wheatley, a second-round pick out of Colorado, was wearing Samuel's old 22 jersey number.

"I know who wore it," Wheatley said. "They kind of gave it to me but I'm not going to complain, either. A number is a number. The man makes the number. Whatever number they gave me, they gave me so I didn't really care."

Wheatley, one of five defensive players taken in last weekend's draft, said he was spending as much time studying his first NFL playbook as he was trying to impress on the field.

"It's a lot thicker so you have a lot more you have to digest," Wheatley said. "You definitely try to learn as much as you can, as quickly at you can. You stay up to 11 o'clock at night trying to study the playbook, something you really typically don't do in college, so that's pretty much the biggest challenge so far."

Shawn Crable, who will compete for a linebacker spot with first-round pick Jerod Mayo, said the coaches were moving through their instruction quickly.

"They're coaching us a lot now because it's just us here but when the vets get here, they're not going to have time to just baby-sit us and teach us stuff," Crable said. "I'm just trying to soak up everything I can now so it's not that rough of a road when they get here."

Following this weekend's camp, the draft picks and selected free agents will return to Foxborough in mid-May for the team's conditioning program.

"When each player leaves here we'll sit down with each player and tell them the things that they should do between now and when they come back on May 15," Belichick said. "Some of those things need to be done in a team setting and we'll take care of that when that time comes, but in the meantime, there are a lot things players can work on individually."