"He actually was at the park one time when he was about 2 years old and I was with the Giants," Blackley said. "But he was out of it and just a baby, really, so he doesn't remember."
Tristan was also in attendance in Kansas City twice last season when Blackley was pitching for the A's, but he never got into the game.
Friday night, Blackley entered the game with a runner on first and one out in the eight inning, with the Astros holding a tenuous 2-1 advantage.
Blackley promptly induced a double play to end the threat and let loose a vigorous fist pump and shout on his way back to the dugout.
"I honestly didn't think about [my son watching] while I was actually on the mound," Blackley said. "It was just a big time in the game. Every chance we get to get a win like that, you have to seize that."
Astros manager Bo Porter said the escape marked "the biggest outs of the game." As Blackley returned to the dugout, Tristan, 8, frantically waved down his father and Dad shot him a smile.
"It's a feeling of joy to have him there," Blackley said. "First thing I heard when I came out of the locker room after the game was him telling me, 'Good job, Dad!' That's so cool."
"He's an aspiring little baseball player," Blackley said. "To perform like that in front of him, it might give him the drive to do this, too. I mean, whatever he chooses to do in life, I'll support him no matter what. But if he chooses baseball, he's got to see me in person now and see me succeed. Best feeling in the world."