A few hours later, Seager was staring at Roenicke with a full head of steam. Pinch-hitter Justin Ruggiano's sixth-inning single set Seager in motion from second base and Roenicke was flapping his right arm like a windmill.
Message delivered and Seager sent one himself.
Seager went belly first across home plate but his Major League debut was far from a belly-flop. The top Dodgers prospect showed why the front office wouldn't relinquish him in various trade scenarios, including ones that could have landed pitchers Cole Hamels or David Price.
The Dodgers bullpen again gave up a lead in a four-run eighth, as the Padres rallied for a victory at Petco Park.
That took some shine off the bright potential displayed by Seager, who was summoned from Triple-A Oklahoma City earlier in the day. But the disappointing loss and lost opportunity to go 7 1/2 games ahead of the San Francisco Giants couldn't eclipse Seager.
Seager, 21, went 2-for-4 with two RBIs and two runs scored. He was smooth at shortstop, where he collected a put-out, five assists and made a nice diving stab in the hole on Derek Norris' infield single.
"He was good,'' Dodgers manager Don Mattingly said. "He looked really good.''
Seager drove in the go-ahead runs in the sixth inning, when his single to center field scored Carl Crawford and Yasmani Grandal and put the Dodgers ahead of the Padres, 5-4. That he had the green light against the left-handed Marc Rzepczynski spoke volumes.
"That's a situation where they can try to let you do something and it was nice that I could get the job done," Seager said.
In the fifth, Seager collected his first Major League knock when he laced a double down the right-field line.
"The first hit, that was really cool,'' Seager said. "That was my first thought where I was like, 'Wow, I'm actually here.'''
Seager said he knew where that baseball will end up.
"I think my parents will probably take that one for sure,'' he said.
His folks were in the stands and Seager said he stole a couple peeks.
"I did every once in awhile, and to see them smile was nice,'' Seager said. "It kind of made me settle in a little bit.''
But he didn't see his mother Jody's tears of joy after his first hit.
"I didn't look at her then,'' he said. "I was shocked at that point.''
The Dodgers felt likewise when their bullpen blew a 7-4 lead. And Seager's coming out party was muted in the L.A. clubhouse.
"It would have been nice to win,'' Seager said. "But I still had fun in my first day.''
Jay Paris is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.