Celtics' Robert Williams admits he messed up by missing flight

Prospect Profile: Robert Williams (0:45)

Robert Williams from Texas A&M is physically dominant and a skilled defender. (0:45)

BOSTON -- Celtics first-round draft pick Robert Williams took responsibility for the missed flight that caused him to miss Boston's first summer league practice Sunday and admitted it didn't help the "bad image" people have of him.

Williams, of Texas A&M, was projected as a lottery pick but slipped to Boston at No. 27 amid concerns about his work ethic. The day after the draft, Williams overslept for an introductory conference call. Then, two days after being formally introduced in Boston last week, he missed a flight back for the start of summer workouts.

"I went home, did a couple of things, then just a missed flight," Williams said Tuesday before Boston's summer squad practiced at the team's new Auerbach Center. "Missed communication by me. It's all on me. So we're going to push forward and move past that."

The Celtics emphasized work ethic to Williams when he first arrived in Boston last week, and the 20-year-old rookie referenced hard work seven times during his introductory news conference on Friday.

The team reaffirmed that message when Williams arrived tardy to Boston over the weekend.

"Just accountability, which they stressed to me a lot when I first got here," Williams said. "Just accountability and just stressing that this is a job. Things are different in college so just knowing what you have and the opportunities are limited."

Williams admitted he got some stern advice from Boston brass.

"They discipline you with words more than you may know," Williams said. "Maybe a couple extra sprints or something like that, I don't know."

Asked if the two missteps to start his pro career were a wake-up call for him, Williams admitted they were.

"Definitely. I talked to Coach [Brad] Stevens when I got back and he obviously explained to me about the opportunity. There's not that many so definitely a real wake-up call," Williams said.

Celtics assistant Jay Larranaga, who will coach Boston's summer squad in Las Vegas starting later this week, did offer praise for Williams, based on what the team has seen since his arrival.

"He dunks with his elbows, which is a really positive thing," Larranaga said with a laugh. "He's been really, really good. Really focused. Picked up the points of emphasis that we had [Monday] in practice really well. Seems very coachable. Like we said, this is the beginning of the process for him and for the summer league team. Day 1 was good."

Later Larranaga added: "He's volleyball-spiking shots and catching the ball with his elbows. He can make an impact on both ends of the floor when he plays with great effort. He has that length and athleticism. I think he's a very unselfish player. That's really important in our system."

On Tuesday, the Celtics also formally introduced free-agent signing Brad Wanamaker. The 28-year-old combo guard has played both in the G League and overseas while waiting for an NBA opportunity. He turned down millions of dollars overseas to sign a minimum-salary deal to be with the Celtics this season.

"Over the past couple years, I thought I was ready for the jump. The opportunity wasn't there," said Wanamaker, who was named Turkish League Finals MVP while leading Fenerbahce Ulker to its third straight title. "Obviously, you leave a lot of money on the table coming here, but I'm back in America. It's a dream come true to play in the NBA and with a team like Boston."

Wanamaker adds guard depth, particularly as the Celtics wait to see if they can bring back Marcus Smart, a restricted free agent.

Wanamaker will wear No. 9 with the Celtics and, with Rajon Rondo set to sign with the rival Los Angeles Lakers, Wanamaker playfully emphasized there was no message in his jersey number.

"Obviously, Rondo was a great player for Boston in his time here. It was a number that was available," Wanamaker said to laughter. "There's no meaning toward it. It just was a number that was available."

Wanamaker played in Germany with Celtics big man Daniel Theis, who joined the team last season. Theis offered a strong vote of confidence for joining Boston.

"A great group of guys, hard workers, a young core of guys who are hungry to win," Wanamaker said. "I'm all about trying to help a team win and this is a perfect situation."