Morrison, who spent four injury-plagued seasons in the big leagues with the Marlins, went on the 15-day disabled list Wednesday with a right hamstring strain.
"Not too happy about not being able to compete, but they say everything happens for a reason," Morrison said. "I'm not quite sure what that reason is right now, but I'm not looking at half a season like I was the last couple of years, so I'm happy about that."
Rather than wait and see whether Morrison could stay healthy a full year, the Marlins signed free-agent first baseman Garrett Jones this past offseason and traded Morrison to the Mariners for reliever Carter Capps.
In 363 games, Morrison batted .249 with 42 homers and 162 RBIs. Asked whether he hoped to prove the Marlins made the wrong decision, Morrison said that wasn't his main objective.
"I hope that I prove that they did," Morrison said. "It's not like I'm going out there with that in mind, but if I prove that they did then that means I'm playing well and helping my team win, and that's what I want to do."
Buck started Sunday's finale and hit eighth in the order. In his two seasons with the Marlins, he hit .213 with 28 homers and 98 RBIs. He came back to Marlins Park as a member of the Mets last season.
"Even being a visitor I want them to move the fences in, but we know that's a conversation we shouldn't bring up," Buck joked. "But now that I'm away, I can bring it up."
Christina De Nicola is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.