Blair, who is 6-foot-5, 225 pounds, has a three-pitch mix, including a fastball that can touch 94 mph and a curveball and changeup. He can throw strikes with all three and he has some late sink to his fastball.
"He led the Cape Cod League in ERA last year," D-backs scouting director Ray Montgomery said. "I've seen him 93-96. He's got a plus changeup, as does Shipley. They go about it differently. Blair is a little more physical. But both are strike-throwers and eat innings, but big physical guys on the mound. That's what we're looking for."
Blair 21, was 5-5 with a 2.85 ERA last season, earning All-Conference USA first-team honors.
Baseball America reported recently that Blair tested positive for the banned stimulant Adderall. Montgomery was asked if there was any hesitation in taking Blair after that.
"None," Montgomery said. "I had a lengthy conversation with him during our pre-Draft workout about it. He was very upfront about the situation. He sought myself out and [general manager Kevin Towers] and wanted to talk about it. It was just a situation he's truly regretful for and he wants to get past it and move on. That there was just an incident there. He was regretful about it and remorseful. I thought it was true to his character and the type of guy that we want to add to the system that he would search me out prior to the results being released."
Blair will likely throw a limited amount of innings for Arizona this summer, possibly in rookie ball or Class A South Bend.
As for Williams, he played shortstop in high school, but the D-backs see his future as a corner outfielder.
One of the younger players in this Draft class, the 17-year-old is 6-foot-2, 215 pounds and has tremendous raw power.
Williams batted .333 with seven doubles, four home runs and 13 RBIs last year and won the Home Run Derby in both the 2012 Perfect Game All-American Classic and the Under Armor All-American Game.
"The tools, again, the athleticism," Montgomery said about what drew the D-backs to Williams. "There is an unteachable [power] tool in there. He's young and has a lot of baseball ahead of him. I'm excited to add that type of power. It's getting harder and harder to find."
Williams has committed to play at Louisiana State University, but Montgomery said he did not anticipate any trouble signing him.
Day 2 of the Draft continues with Rounds 3-10, streamed live on MLB.com on Friday, beginning with a preview show at 9:30 a.m. MST. And Rounds 11-40 will be streamed live on MLB.com on Saturday, starting at 10 a.m.
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.