This was definitely a cool day.

Walker, Seattle's top pick in the draft, agreed to a deal on Friday that included an $800,000 signing bonus and was assigned to the Mariners' rookie league team in Peoria, Ariz.

"It's crazy. It's a dream come true," said Walker, a 17-year-old right-hander from Southern California's Yucaipa High School. "Seeing all the cool players. And this interview <emdash /> all these people!"

The 6-foot-4, 190-pound Walker, who was selected with the 43rd pick in this month's draft, also was excited about his hotel room in downtown Seattle. The Mariners upgraded it to a suite, complete with its own living room and a bedroom down the hall.

Walker texted pictures of it to his mother, Nellie, on Thursday night.

"It's been so surreal. Unbelievable," Nellie said from inside the Mariners' dugout, a few feet away from the second of her four children. "Everyone at home knew it was going to happen, because growing up he was so athletic. But for it to happen, it's still unbelievable."

Agent Larry Reynolds confirmed the signing bonus to The Associated Press as he stood behind home plate and watched his client visit with the Mariners during batting practice.

Walker was 10-4 with a 1.77 ERA this season for Yucaipa, which is east of Los Angeles on the way to Palm Springs. He struck out 93 in 67 1-3 innings.

He also played center, forward and some guard while leading his school's basketball team with 21 points and 15 rebounds per game.

Mariners scouting director Tom McNamara said Yucaipa's baseball coach told him Walker has "a little (Kevin) Garnett in his game," referring to the versatile star for the Boston Celtics.

McNamara said Walker, who has a 95 mph fastball, can be a "front-of-the-rotation" pitcher for Seattle perhaps within four years.

Seattle signed 10 other draft picks on Friday: right-hander Luke Taylor (ninth round), right-hander Tyler Burgoon (10th), infielder Stefen Romero (12th), left-hander Jason Markovitz (13th), right-hander Jandy Sena (23rd), catcher Andrew Giobbi (32nd), outfielder Ethan Paquette (35th), right-hander Joshua Krist (39th), catcher Billy Marcoe (41st) and right-hander Tim Boyce (44th).