As he delivered his first pitch to Jedd Gyorko, Rusin was called for a balk by the second-base umpire, John Tumpane.
Derek Norris, who was standing on third base, trotted in for what appeared to be the game-tying run.
Not so fast, though.
The umpire crew conferred in the middle of the infield and quickly overturned the call, much to the chagrin of Padres interim manager Pat Murphy, who argued the call.
The confusion stemmed over whether Rusin was pitching out of the stretch or from the wind-up.
"His motion from the full windup and his motion from the stretch is very similar setup," Murphy said of Rusin. "The balk was called by the second-base umpire because he felt like he didn't come set, which he doesn't do in his full windup.
"Our argument is, one, he called the balk already, and it's a deception to the hitter to not know, because it looks exactly the same in the setup. Because what he did, instead of coming set and stopping, he just brought his hands together and pitched."
Murphy's other issue was the umpires disallowed the pitch and Gyorko, instead of facing a 1-0 count, went back to a no count.
In a sense, it was like the play never happened.
Murphy disagreed and was ejected by third-base umpire Dan Iassogna, his third ejection since taking over the team in mid-June.
Rusin regrouped and got Gyorko to ground out to Nolan Arenado at third base to end the threat and the inning as the Rockies maintained a 1-0 lead.
Rusin said afterward that he could see where the confusion came from.
"They didn't know I was in the windup. The guy behind me called the balk, and he said, 'You're in the stretch. You can't do that.' And I said, 'No, I was in the windup,'" Rusin said. "So they were just a little confused about that and got together and sent the runner back to third."
Colorado manager Walt Weiss said Rusin, a left-hander, has a little funky setup to begin with, which could certainly lead to confusion.
"It looked funky because Chris was using that roll-through windup, which has been very effective for him," Weiss said. "He implemented it probably a couple weeks ago, and it creates some deception, some timing issues for the hitter.
"So it looked funky, but he was pitching out of the windup. But he rolled through his delivery, and so the ump just assumed it was a balk there because it looked weird. But the fact that he was going from his windup, he can do anything he wants."
Gyorko felt the umpires ultimately got the call right.
"I think the umpire got it complicated," he said. "I saw him in the windup. I think he thought he was in the stretch. Obviously, when he doesn't come set or doesn't pause, it's a balk. I didn't think it was a balk. You'd like to get that ball back but it didn't change anything."
Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.