"We know what kind of club we have," Mattingly said. "But we also know we're going to be challenged depth-wise. We need a little bit of luck, everything kind of falling in slots for us. In the last probably month and a half, it's probably fallen the wrong way. It's put us in a bind."
The inexperience was revealed on Monday.
Right-hander Jake Esch, making his second big league start, was staked to a 2-0 lead in the first inning, and he held it until the fifth inning, before he hung a breaking ball that Freddy Galvis blasted for a two-run homer. The Phillies took a 3-2 edge in the inning on Cesar Hernandez's grounder that was misplayed for an error by shortstop Miguel Rojas, which allowed Peter Bourjos (who tripled) to score from third.
And in the seventh inning, reliever Austin Brice, in his fourth big league game, committed two throwing errors. The Phillies added three more runs in the inning, with two earned.
"We have some guys out there who basically should be coming up, but not necessarily having to be part of a one-run game or something like that," Mattingly said. "But that's where we are right now."
Esch is filling the rotation spot vacated when David Phelps went on the disabled list with a left oblique strain.
"We scored two, I gave up three, just not quite good enough," Esch said. "It's improvement from the last one, so that's a positive step in the right direction for me personally. But it ended up as a loss for the Fish again, so got to be a little bit better."
As the inexperienced pitchers look to find their stride, the offense continues to not cash in with runners in scoring position. Miami scored two in the first inning off Jerad Eickhoff, and that was it.
The Marlins had second and third and one out in the second inning and a runner on third with one out in the fifth inning. In both cases, Eickhoff worked out of trouble.
"That first inning, we kind of jump guys," Mattingly said. "Then they're going to start pitching. They're going to start using their breaking ball, start using their changeup. They're going to start pitching backwards, and they're going to do some things.
"We don't seem to be able to make that adjustment. That's been kind of the one constant we've seen all year."
Joe Frisaro has covered the Marlins for MLB.com since 2002. He writes a blog, called The Fish Pond. Follow him on Twitter @JoeFrisaro and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.