Rated No. 154 in MLB.com's Top 200 Draft prospects, McCanna watched eagerly from his home in The Woodlands, Texas, expecting to be taken on the second day of the MLB Draft, only to fall to Houston at pick No. 379.
Both McCanna and Astros director of amateur scouting Mike Elias were surprised when the local right-hander was still available in the 13th round, and Elias pounced on the lifelong Astros fan.
"I have no idea," McCanna said shortly after the Draft concluded. "I was ready to sign. I'm ready to play and I think that's how the Draft worked. There were guys ahead of me who kept falling and falling."
McCanna signed with the Astros on Wednesday morning, though terms of the deal were not immediately known. By signing, he forgoes a final season at Rice, where he spent most of his final two years as the Friday night starter with a sub-3.00 ERA.
McCanna was one of eight Astros draft picks to sign on Wednesday, including sixth-round pick Nestor Muriel of the Carlos Beltran Baseball Academy. McCanna was joined by fellow pitchers Adam Whitt (16th round), Makay Nelson (20th round), Alex Winkelman (21st round) and Zac Grotz (28th round). Arizona State center fielder Johnny Sewald (14th round) and catcher Jorge Martinez of the Carlos Beltran Baseball Academy (25th round) rounded out the Astros signees.
The Astros have now signed 18 of their 42 draft picks, including No. 5 overall pick Kyle Tucker.
McCanna uses a four-pitch arsenal to pitch to contact. He doesn't label himself a strikeout pitcher -- he only fanned 147 in 218 2/3 collegiate innings -- and hopes that some time in the Astros' farm system can polish a few other aspects of his game.
"I'm going to take every piece of information I get from coaches in the organization," McCanna said. "If they can help me get a fifth pitch or help me strike out a few more guys, that would be great."
A self-described baseball junkie, McCanna said he watches baseball constantly. Even after all that viewing, he can't seem to find anyone to compare himself to.
Growing up as an Astros fan made his fall in the Draft a bit more bearable, knowing he's now living out his dream.
"I'm definitely glad with how it turned out," McCanna said. "I'm more than thankful to go play for the Astros."
Chandler Rome is an associate reporter for MLB.com.
This story was not subject to the approval of Major League Baseball or its clubs.