A hernia forced O'Neill to move to shortstop last year, and despite the position change, he made the Canadian Junior National Team. In his time with the National Team, O'Neill had the opportunity to play against the Rangers' instructional team. He collected several hits against Texas prospects, including a home run. O'Neill, who shows speed on the basepaths, attends Garibaldi Secondary School in Maple Ridge, British Columbia.
"The unique thing about the Canadian team is they play in Florida and Arizona and play against the Class A, [Class A Advanced] and sometimes Double-A prospects," McNamara said. "You're seeing 17- and 18-year-old's get up against stuff that they're probably not going to see here in the spring against high school pitchers. So we saw him really handle some really good pitchers, older guys that didn't care who he was -- they went right after him and it was really good to see."
His father, Terry, is a former Mr. Canada and taught O'Neill about weight lifting. At 6 feet, 200 pounds, he is solidly built and earned the nickname "Tank." He is an aggressive hitter and should develop good power.
As a hard-nosed member of the Langley Blaze travel team, O'Neill has inevitably been compared to Brett Lawrie, who played for the Blaze as a high schooler. O'Neill is committed to Oregon State.
In addition to catcher-turned-shortstop-turned-outfielder O'Neill, the Mariners took Emilio Pagan out of Belmont Abbey College in the 10th round. Pagan excelled at third base for the Crusaders, but it's on the mound where the Mariners believe his future lies. Similarly, Texas prep Corey Simpson, taken in the sixth round, will be expected to make the switch from catcher to outfielder if he signs with the club.
"Sometimes going into your senior year during your spring season, some people think their value is increased because they're a catcher," McNamara said. "Well, he's played all over the place, too, but we see him as an outfielder. Good sized kid, good looking hitter."
Seattle selected left-handed pitcher Ryan Horstman in the fourth round. The redshirt freshman out of St. Johns University in New York didn't play baseball for two years, repeating his senior season of high school due to academic issues and sitting out his redshirt season for the Red Storm.
The Mariners also added left-handed pitchers Tyler Olson from Gonzaga University and Jacob Zokan from the College of Charleston in the seventh and ninth rounds, respectively.
"There are certain rounds where in your mind you're like, 'What we need is some left-handed pitching,'" McNamara said.
The Mariners rounded off the Draft's second day with a pair of shortstops, taking East Carolina University's Jack Reinheimer in the fifth round and Oregon State's Tyler Smith, who was named First Team All Pac-12 in back-to-back seasons, in the eighth round.
"Again, you want to take some shortstops in there and they go like this off the draft board," McNamara said. "Shortstops, pitcher, catcher, center fielders go like that. If he can't make it as an everyday shortstop, you've got a guy that can play second, third, and they run and swing the bat OK so we're happy."
So far, the Mariners have taken an aggressive approach to the 2013 Draft, selecting athletic players that they believe can be developed, often into unfamiliar positions. And if there is a gem to be found, he may still yet to be selected.
"I keep telling our guys the next 15 picks are just as important as the last five or six," McNamara said. "We've taken a couple of good players the last couple years here outside of the fifth round and we plan on doing that. Some teams, you can tell as the Draft goes on that the white flag's coming up a little. We just want to keep grinding until the last pick."
Day 3 of the Draft continues with Rounds 11-40 streamed live on MLB.com on Saturday, starting at 10 a.m. PT.
MLB.com's coverage includes Draft Central, the Top 100 Draft Prospects list and Draft Tracker, a live interactive application that includes a searchable database of Draft-eligible players. You can also keep up to date by following @MLBDraft on Twitter. And get into the Draft conversation by tagging your tweets with #mlbdraft.