And so was the San Francisco Giants' often leaky defense.
With the help of several outstanding defensive plays, Cain threw the first perfect game in Giants franchise history, striking out a career-high 14 batters as San Francisco blanked the Houston Astros 10-0.
"This is incredible right now," Cain said. "That's was something that obviously I'm never ever going to forget. But it was unbelievable from the beginning. And the guys did a great job of being able to make it in a way relaxing for me because they were able to get on the board early and keep scoring runs, and there's nothing better than that when the guys go out there and do that."
Cain's 125-pitch gem -- the most pitches ever thrown in a perfect game -- was challenged twice.
In the top of the sixth, Chris Snyder hit a flyball to deep left-center that was caught by Melky Cabrera, who made a mini-leap at the wall to prevent Snyder from getting an extra-base hit. Cain said afterward that he thought Snyder's drive was going to clear the fence.
But the most memorable play came in the top of the seventh, when right fielder Gregor Blanco ranged far to his right on a drive hit by Jordan Schafer. Blanco made an incredible diving catch on the warning track in center field to keep the perfect game intact.
"As soon as he hit that ball I said to myself, you've got to run as hard as you can, you got to try to catch that ball," Blanco said. "This is going to happen, you're going to be part of it. I wasn't sure if I was going to catch it or not, I just said to myself, just run. And I did, and it was great."
"When I hit it, I looked up and saw (Angel) Pagan and I knew there was no way," Schafer said. "I didn't even look at Blanco. Blanco made a good play. You need those plays in a perfect game. You can't take anything away from him (Cain). He was outstanding tonight."
In the ninth, Brian Bogusevic and Snyder both flied out to left, and Jason Castro grounded out to third. Even the last out was difficult -- third baseman Joaquin Arias had to handle a tough hop, slightly lost his balance, steadied himself and threw a strike to first.
The Giants made quick work of Astros starter J.A. Happ. Cabrera, Brandon Belt and Blanco all hit two-run homers. The Giants have hit five home runs in two home games after going homerless in the prior 16 games.
Happ was shelled for eight runs on 11 hits in only 3 1/3 innings, raising his ERA from 4.54 to 5.33.
After the fifth inning, with the Giants comfortably in front by double digits, the focus solely was on Cain and his pursuit of recording 27 straight outs.
It is the second time in baseball history there have been two perfect games in the same season, as Philip Humber of the Chicago White Sox pitched one April 21 against the Seattle Mariners. Dallas Braden of Oakland and Roy Halladay of Philadelphia both did it in 2010.
It also is the first perfect game in Giants franchise history and is the third time in 13 days a pitcher hasn't allowed any hits. Johan Santana of the New York Mets threw a no-hitter on June 1, and six Seattle Mariners pitchers combined for a no-hitter Friday.
The last time there were two no-hitters as close together as the five-day span between the Mariners and Cain was when Minnesota's Francisco Liriano beat the White Sox on May 3, 2011, and Detroit's Justin Verlander beat the Blue Jays four days later.
The Giants' last no-hitter was by Jonathan Sanchez in 2009, and that almost was a perfect game. Sanchez didn't allow a baserunner until the eighth inning, when third baseman Juan Uribe was charged with an error.
It was the 22nd perfect game in history but the first time the pitcher had 14 strikeouts in a perfecto since Sandy Koufax in 1965.