It was soft, melodic, and directed at a 2-month-old boy smiling at him through the screen of a smartphone.
The night before the Dodgers' first workout, using FaceTime to connect with a certain bassinet back in Evansville, Ind., Mattingly verbally rocked his infant son to sleep.
"Worked too," he said. "Just kept talking till his eyes closed."
Talk about a Donnie Curveball. The Dodgers manager, at age 53, helped engineer the team's most unusual transaction this winter when he and wife Lori added a loud and spunky infielder named Louis Riley Mattingly. After spending last summer running a clubhouse filled with babies, Mattingly actually had one of his own, born on Nov. 29, seven pounds and dark haired and, yeah, Daddy knows exactly what you're thinking.
"We're out shopping for some baby stuff and the salesperson sees Louis and asks if he's my grandchild," Mattingly said. "I'm like, OK, now it starts."
For Mattingly, as always, it starts with family, so after four years of marriage, he said it felt only natural for he and Lori, 44, to add to their blended brood of five boys.
"I love kids, I love being a dad, and we decided if this was meant to happen, it would happen," he said.
That it happened this winter made it even more compelling considering the Dodgers were ankle-deep in front office turnover and dugout uncertainty. Yet Mattingly brought the same calm to his Evansville home that he brings to the dugout, standing by Lori as she gave birth to their first child together, after which he canceled his expected appearance at baseball's winter meetings so he could change diapers and do midnight feedings.
"It's just so great, so important, so much, it's so amazing," he said.
It has been 23 years since Mattingly had dealt with a newborn, so he had to brush up on some techniques, beginning from the bottom up.
"I have to admit, his diapering skills were a little slow at first," Lori said. "But he hung in there as calm as always, he wouldn't quit, and he figured it out."
Then there are the newfangled car seats, which Mattingly talks about in tones of awe and wonder, as if describing a great pitch or top prospect.
"Can you believe that you can just snap the seat into the base, then, when its time to get out, you just snap the seat out of the base and put it right in the stroller?" he said. "I've never seen anything like it."
Don't forget baby monitors, which Mattingly breathlessly says have been fitted with a new technology that rivals the Mars rover.
"In the old days you could only hear the baby, but now you can actually see him on a video screen," Mattingly said. "I mean, you can really watch him sleeping!"
Oh, yeah, sleeping. Before coming to Camelback Ranch last week, Mattingly hadn't been doing much of that, napping only about three hours at a time with the baby since November, and that part never gets any easier.
"It turns out there's some things you don't forget," said Mattingly. "Like, how it hard it is go without sleep."
When he wasn't dozing or changing or feeding, he has been reading a different kind of scouting report. It's called "What To Expect The First Year," a parenting book he says has taught this old manager new tricks.
"Do you know babies are now supposed to sleep on their backs instead of their bellies?" he asks. "Or that it's good to sing to him even though I don't know any songs? I can just make up words and sing and it relaxes him? It's pretty cool."
Not that there haven't still been surprises, like unofficial bans on the most obvious baby products ever.
"I tell my wife we need baby powder and she says, 'We can't use baby powder anymore, it's not good for him because it could get in his lungs,' and I'm like, what?" Mattingly said. "Who would have thought we'd reach a point where babies couldn't use baby powder?"
Mattingly also has had some difficulty coming to grips with the fact that enamored strangers want to touch little Louis, and friends even want to — gasp! — hold him.
"The first time I let somebody hold him, he looked at me like I was crazy, he's so worried about somebody passing on colds or sicknesses," Lori said. "So he holds the baby close and won't let anyone get near. A mom comes up and he's like, 'Back off, Barbie!'"
Just as Mattingly is a player's manager, he's also a baby's manager, re-learning nursery rhymes, reading to him deep into the night, even giving Louis baseball lessons out of the bassinet.
"Every day, Donnie talks to him about switch-hitting, goes through the motions and everything," Lori said. "Switch-hitting. A baby."
There were tears when Mattingly left Lori and Louis behind to fly to spring training last week, but a couple of days after he arrived, his joy at being a father again was palpable. His constant smiles cut through the stress of questions about working for new bosses Andrew Friedman and Farhan Zaidi, of whether he feels he is on a one-year tryout, and will he ever lead them past the St. Louis Cardinals?
"No matter who is the boss, you've got to do the job, and if you're not doing the job, you're in trouble," Mattingly said. "I look at it like, this is a bit of a re-set for all of us, I welcome the way Andrew and Farhan do things, they've got a well-rounded view of our players, I'll learn from all of them and we'll move forward together."
The most unusual bond being between the manager and his Cy Young/MVP winner, considering Clayton Kershaw and wife Ellen also had a baby this winter.
"When the manager shows up with a new baby at the same time his Cy Young pitcher has as new baby, that's sort of interesting, huh?" Mattingly said with a grin. "I'm actually try to get my little guy together with Clayton's little girl. Now wouldn't that be something?"