Diaz, an 18-year-old right-hander from Puerto Rico, was the team's third-round pick (98th overall). Pike, 18, is a left-hander from Winter Haven, Fla., who went 8-2 with a 0.51 ERA with 134 strikeouts in 82 innings his senior season of high school. He was the Mariners third-round supplemental pick (126th overall).
Both Diaz and Pike were at Safeco Field on Thursday and will report to the Mariners' Rookie affiliate in the Arizona League.
"It's amazing," Pike said of his Seattle tour. "It's a great experience just to see how well they treat you. All the guys, everybody says they're all stuck up and everything, but they're all nice guys."
Pike signed with the club for more than double the recommended slot for a third-round compensation Draft pick, according to figures obtained by MLB.com. He will receive $850,000, well above the $370,800 assigned value for that pick in MLB's new system.
The Mariners also went above the assigned value to land high school shortstop Joe DeCarlo, who was one of 25 Draft picks whose signings were announced by the club Wednesday. DeCarlo signed for $1.3 million, which is more than the assigned value of $806,000.
The Mariners have been aggressive in getting deals with many of their top picks. Fifth-rounder Chris Taylor signed for $500,000 (assigned value $264,500) and Timmy Lopes got $550,000 in the sixth round (assigned value $198,100).
The Mariners still haven't signed first-rounder Mike Zunino or eighth-rounder Nick Halamandaris.