On Sunday, soon after the Bucs had tied it in the seventh when Brock Holt led off with a triple and eventually scored on a balk by lefty reliever James Russell, Grilli (1-6) surrendered a two-run homer to Alfonso Soriano in the eighth.
There was another similarity between the losses, as well as to a recurring issue: An inability to close offensive deals, critical to a club with Pittsburgh's relatively shallow lineup.
The Bucs went 0-for-11 with men in scoring position on Sunday -- including Gaby Sanchez striking out and Pedro Alvarez flying out for the game's final two outs against Carlos Marmol with the bases loaded.
"I would put missed opportunities at the top of the list, most definitely," manager Clint Hurdle said.
Speaking of missed opportunities, a 2-4 homestand against the Astros and the Cubs would also fall into that classification. After a third straight loss to Chicago, it was no longer easy to find solace in the Cardinals' own weekend losses that kept the Pirates in the playoff picture.
"Had the teams we're competing with to make postseason made positive runs, it would've been a very, very tough week," general manager Neal Huntington said. "We didn't capitalize on opportunities [to make up ground], but the optimist in you says there are still plenty of opportunities in front of us.
"We need to get back to playing good baseball, to focusing on that day's game and doing what we did to put ourselves in position to be in a race. And if we do that, we'll still find ourselves in a good spot."
In the three games, Pirates batters were 3-for-21 with runners in scoring position. The Cubs outscored Pittsburgh, 20-7, after coming off three straight losses in Washington in which the Nationals had outscored Chicago, 29-8.
"They played better defense than us, they pitched better than us, they hit better than us for three games," Hurdle said. "You can go to a lot of other places, but don't really need to."
Thus the Cubs wrapped up their first road sweep of the season, and first since Aug. 1-4, 2011 in -- where else? -- Pittsburgh. The last time the Cubs traveled somewhere else with their brooms? Sept. 17-19, 2010, to Miami.
Chicago had arrived along the shore of the Monongahela on Friday with an away record of 16-52.
Russell's lapse cost young lefty Chris Rusin his first Major League win. Making his third big league start, the 25-year-old handcuffed the Bucs for five innings, allowing four hits besides Andrew McCutchen's first-inning homer, with three walks and four strikeouts.
The Pirates' own rookie southpaw, Jeff Locke, one-upped Rusin across the board, but unfortunately for him that included giving up one more home run. In six innings, the Bucs' southpaw allowed five other hits and had six strikeouts without a walk.
The bottom four of the Cubs' lineup, including Rusin, came in with six hits among them in 76 at-bats. Not an outrageously unusual situation for September, with its new faces and trials. What was unusual was the damage to Locke coming from that quartet, the two solo homers representing the only runs he allowed.
Trailing, 2-1, the Bucs appeared set up in the fifth, because Locke's leadoff single and an ensuing infield hit by Holt meant two on with no outs and the business part of their lineup coming up. Nothing doing, though, starting with Starling Marte's strikeout after two failed bunt attempts.
"Those were planned. He got the signs," Hurdle said. "We tried to find some spark on offense, move some people up and create scoring opportunities and throw something out there for Andrew [McCutchen, the next batter], which is never a bad idea."
Those inabilities to lay down bunts may have been what McCutchen had in mind when he said, "Guys gotta get their jobs done. We've gotta get our focus back to that. We've gotta keep doing the simple things that help you win games the right way."
McCutchen followed Marte by flying to center -- which could have scored an advanced runner from third base -- and Garrett Jones' whistling liner to right became foil for a nice sliding inning-ending catch by Dave Sappelt.
Until McCutchen ended the improbable silence in the final and sixth game of the homestand, the Pirates were unable to hit a single home run against two of the most permissive pitching staffs in the league. Houston ranks second in most home runs allowed (158), barely behind the Mile-High Rockies. The Cubs (156) are a step behind the Astros.
McCutchen's blow wasn't worth lasting bragging rights. Within the space of three batters in the fourth, the Cubs launched twice as many home runs, with Josh Vitters (5-for-67 starting the game) hitting his second of the season and Anthony Recker (0-for-1) hitting the first of his career.
"A real professional outing by Jeff, otherwise. Just a couple of balls he tried to get in but left a little out there," said Hurdle, particularly impressed by the six-strikeouts-to-no-walks and the combined 0-for-6 Locke hung on Soriano and Starlin Castro.