PORT ST. LUCIE – Philip Humber, the team’s 2004 first-round pick, was optioned to the minors yesterday after posting a 16.20 ERA in three outings.

Humber, who allowed eight hits and nine earned runs in five innings, was sent packing along with lefty Jason Vargas and righty Marcos Carvajal.

“Obviously, I would’ve wanted to perform better and come out of the gates a lot stronger than I did,” Humber said before last night’s 4-1 victory over Boston. “But that happens, and I don’t know if it would’ve changed a whole lot.”

“I thought at times he overthrew his curveball, overthrew his fastball, overthrew his change-up,” Willie Randolph said. “That’s what happens when young kids are trying to impress you.”

Humber had Tommy John surgery in 2005. He was 3-1 with a 2.37 ERA with Class-A St. Lucie and 2-2 with a 2.88 ERA at Double-A Binghamton before a September promotion to the bigs. GM Omar Minaya, Randolph and pitching coach Rick Peterson gave him the news in a positive fashion.

“They made me feel like I’m one of those guys that they’re gonna count on this year at some point,” Humber said. “And that’s my goal.”

After the game, outfielder Ruben Sierra was reassigned. Sierra reportedly said this week he wouldn’t accept a minor-league assignment, but he told a spokesman late last night that he hasn’t decided yet and would rather not talk.

“We brought him in on a minor-league deal to be insurance,” Minaya said. “That’s always been the plan. Those things were discussed with the agent before he came on board.”

Outfielder Carlos Gomez was optioned and catcher Jose Reyes was reassigned.

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Randolph doesn’t expect to have Duaner Sanchez (shoulder) for Opening Day. Aaron Heilman (elbow tendinitis), out since March 9, hopes to return tonight against Florida. “At this point, it’s nothing to worry about,” Heilman said yesterday. “A little bit of an annoyance and a nuisance. Nothing that I’m too concerned about.”