Frustration, disappointment or bitterness would have been justified.
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Lagares chose resilience.
"Even if I don't play," the 26-year-old centerfielder said, "I have to keep working, because you never know."
Lagares blasted a pinch-hit, three-run homer off Tommy Kahnle in the eighth inning of the Mets' 12-3 win over the Rockies on Thursday afternoon.
"I think he's got something to prove," manager Terry Collins said.
Curtis Granderson has seen it every day since the Mets brought in Cespedes, a bona fide No. 3 hitter who was an All-Star last year.
"Juan still comes in each day ready to work," Granderson said. "I see him in the gym, in the batting cage, on the field, doing his things in the outfield. Every day. He played rightfield for the first time in a long time in Tampa. He's just got to continue to adjust and go with it."
After winning a Gold Glove Award and showing promise offensively last year (a .281 batting average in 416 at-bats), Lagares signed a four-year, $23-million contract extension during spring training. But he has been underwhelming this season, posting a .259/.287/.353 slash line.
"Definitely a difficult situation to be in," Granderson said, "where you go from playing every day and then obviously someone comes in and we're logjammed up in the outfield. I understand that he may not get to play as much as he would like to, but when given the opportunity to play, trying to step up and maximize it as best he can, I think he's been doing an amazing job of it."
Case in point: Lagares' pinch-hit home run to left-centerfield, which came on a 1-and-2 changeup.
"Today I think is the perfect day to see that," Lagares said. "I didn't start the game, and I had the opportunity to come in and got the homer. You have to be ready for everything, even when you don't start."
Each opportunity Lagares gets is precious now. That's one motivator he didn't have before Cespedes became a Met.
"There's nothing I can do about it,'' Lagares said, "so just keep working. I think that's the main thing."