Murphy has just three hits in his last 26 at-bats and still has no home runs this season. He came off the bench in three of his last four games and didn't play in Monday's series opener against the Cubs.
"Right now, he's going outside the strike zone a little bit, where he's swinging at some pitches he has no chance to hit out of the ballpark," Collins said. "When he's swinging good, he's a good enough hitter where eventually he'll hit some homers."
He said when Murphy is swinging to his maximum capability, he hits all types of pitchers and completely changes the Mets lineup.
With a trip to play the Dodgers on the horizon, Collins said Murphy may play against left-hander Chris Capuano, but likely not Clayton Kershaw.
"I'm not sure Kershaw's a fair match with his breaking ball," Collins said. "But it might take [Capuano's] changeup away a little bit."