The Dodgers rank eighth in the league with a .250 team batting average, but are next-to-last in runs scored, 13th in runners stranded, 15th in slugging percentage and 10th in on-base percentage. They've been shut out 10 times, exceeded only by San Diego and Washington.
Add it up and it resulted in the subtraction of the 64-year-old Pentland, a quiet but popular teacher who took the fall.
General manager Ned Colletti said he and Mattingly talked about making a change at the All-Star break, but held off hoping that the offense would awaken. It didn't.
Colletti said the decision stemmed from a combination of Pentland and the lack of production, not just one or the other or any communication breakdown.
He said he was hopeful it would shake up his club's hitters. This is the third midseason change of hitting coaches in Colletti's six years as GM. He also replaced Eddie Murray with Bill Mueller in 2007 and Mike Easler with Mattingly in 2008.
"It's a lack of results, and in some cases a lack of focus," said Colletti. "You hope with a new voice, somebody sees that a good man was let go and you point to yourself that I've got to be better at what I do.
"We don't lack for talent. Are we the '27 Yankees? No. Look at the offensive production of the club and certainly some guys have fallen short, not of expectations not warranted but by the type of performance of the past. This is not about blame. It's being a new voice and a realization that it's got to be better."
Colletti and Mattingly praised Pentland as a master of the swing and a passionate teacher. Mattingly seemed to take the decision especially hard and was noticeably red-eyed Tuesday night, knowing of the upcoming announcement.
"As a player, you've got to know we didn't get our job done," he said. "I know somebody takes the fall, somebody will take the hit. It always made me feel horrible. I know it wasn't their fault. He did everything he could do to help them. It doesn't mean he's not trying or not capable. It's just his voice isn't being heard and it gets down to the bottom line."
Pentland was not in the meeting or available to reporters. Mattingly said "he was hurt, no doubt about it" when told.
Andre Ethier, hitting .299 but lacking the power of his best seasons, said, "It's unfair to lay the blame on one person." He said if dismissing the hitting coach is meant to awaken the offense, it's a stretch.
"We know what's going on isn't acceptable," he said. "If they think anyone in here doesn't think that, they don't have the priorities right. We just have to figure out a way to do it different.
"As a player, you feel responsible for all the things that led to this -- the way the season has been to individual wins to not producing offensively. Guys like Pent have to be the scapegoat; they're put out front."
Aaron Miles, whose .311 average took him from a bench player to an almost-starter, agreed.
"There's not a guy on the team that doesn't feel at least somewhat partly to blame because this is us out there doing it," Miles said. "Hitting coach is the toughest job in baseball. Credit is hard to come by when we're doing well and we do badly and the guy gets the finger pointed at him.
"He's a good hitting coach. This is tough for everybody today. He's very well liked and we know the blame doesn't rest totally on him. It rests on everybody."
Pentland previously served as hitting coach with the Mariners, Royals and Cubs.