But Grilli never had a doubt that he'd be on the mound in September and hopefully October. He continued to live up to his own expectations Sunday, when he closed out the Pirates' 5-3 win over the Cardinals in Game 3 of the National League Division Series.
"No, you can rewind that tape," Grilli said afterward. "I said I was going to be back, and here we go."
Grilli's scoreless ninth inning Sunday was even more crucial after a rare mistake from setup man Mark Melancon.
Melancon hadn't allowed a homer since April 14 -- the only homer he yielded in the regular season -- until he was taken deep by Carlos Beltran in the eighth inning of Sunday's game. The home run tied the score at 3-3 before the Bucs took the lead back in the bottom of the inning.
"If you give a great hitter like [Beltran] a bad pitch to hit, he's going to do some damage," Melancon said. "That's what happened, and at the end of the day, never once did I think we were going to lose that game."
Melancon had as much faith in the offense adding more runs as he did in Grilli shutting the door.
When Grilli returned to the Pirates on Sept. 4 after missing about six weeks, he allowed four runs over his first four appearances. Two scoreless innings later, and manager Clint Hurdle rewarded Grilli with his old job. Back to the ninth inning.
Even Melancon, who was impressive in his own right with 16 saves in Grilli's absence, was OK with the move.
"I think we're always pulling for each other," Melancon said. "Everyone in the bullpen is. Everyone on this team is. It's not really a selfish role or anything like that. We're just pulling for each other."
Since returning to the closer role on Sept. 21, Grilli has performed as well as he did in April. He's thrown 5 2/3 scoreless innings while allowing five hits and striking out four. And Grilli's velocity has nearly returned to full strength, with an average fastball of 93.7 mph, less than a 1-mph variation from his velocity prior to the injury, according to Brooks Baseball.
"He's always worked hard, so that's not a big difference there," Melancon said. "Obviously, he's done great consistently. I wouldn't expect anything less."
Grilli said his strong return came down to motivation. He couldn't see himself on the sidelines while Pittsburgh made a postseason run.
"This is why I signed back here [in 2012]," Grilli said. "I saw the potential of what this team was in the process of doing, the winning ways. I wanted to be with a winning team."