BOSTON — When the Boston Red Sox began their major league spring training camp last February, Daniel Nava could not be found.

Simple reason. Nava was not invited.

The man who went from the Portland Sea Dogs in 2009 to hitting a grand slam on the first major league pitch he saw in 2010, was a forgotten player in 2012.

“Of all the guys that were on the radar, he wasn’t one of them,” Boston manager Bobby Valentine said.

At the end of Sunday’s 12-1 Red Sox win over Cleveland, that loud beeping sound on Valentine’s radar is one Daniel Nava. He notched two RBI with two doubles, was hit by a pitch twice, scored three runs, stole a base and played a solid left field.

Since being called up to the majors on Friday, he is batting .600. He has reached base 12 times in 16 plate appearances (.750 on-base percentage) and has four doubles (1.000 slugging average).

“Daniel Nava’s at-bats, his defense … he has played a very good brand of baseball,” Valentine said.

Asked if he knew what to expect from Nava, Valentine shook his head emphatically.

Who knew?

When Nava, 29, was not invited to major league camp this year, it looked like his baseball career would likely fade away in the minors. Nava reported to minor league camp in March.

“I wasn’t sure what to expect,” Nava said. “I was just out to make the team out of camp.”

The team Nava is talking about was not Boston, but the Pawtucket Red Sox, the Triple-A team he played for all of 2011 (batting .268 with 10 home runs).

Nava was actually relaxed last spring. If you’re not on the manager’s radar, all that’s left is to play baseball.

“I think that helped with the whole process,” he said. “Just going one day at a time, instead of going ‘I got to do this, I got to do that.’

“Sort of a ‘I got nothing left to lose’ mentality.”

But hasn’t that always been Nava’s mentality?

When Nava first came to the Portland Sea Dogs on Aug. 5, 2009, his underdogs resume was already well-documented.

* Cut from his Santa Clara University baseball team, Nava became the team manager and washed the uniforms.

* He transferred to a junior college, batted .430 and made All-American.

* Returned to Santa Clara, batted .395, but was not drafted.

* Received a last-minute tryout for the independent Chico Outlaws, made the team, batted .371 and was the Golden Baseball League MVP.

* Signed with the Red Sox and kept hitting, including a .364 average in Portland that last month of 2009.

* Began 2010 in Pawtucket before a June 12 call-up to Boston, where he hit a grand slam on the first pitch.

Nava ended up playing 60 games for Boston that year, batting .242.

After staying in Triple-A all of 2011 and getting the major league slight this past spring, it looked like Nava’s future in Boston would be only as the answer to a trivia question.

Like other minor leaguers, Nava was called up for a handful of major league spring training games, as a fill-in.

“He made a good impression on us,” Valentine said.

If Nava was slowing showing up on the radar, his start in Pawtucket this season knocked him off, batting .188 through April 23.

But since then, Nava batted .420 in Pawtucket, with seven doubles, a triple and two home runs.

“Arnie (Beyeler, the Pawtucket manager) continued to praise his at-bats and his play in Triple-A,” Valentine said. “When we finally got an open roster spot, we figured we’d take a look.

“And, yeah, he’s playing really well.”

Nava knows how quickly things can go south.

“I’ve learned, and I still have a lot to learn,” he said. “There’s a lot of work to be done.”

And, it seems, there are more chapters to write in the story of Daniel Nava, the underdog who would not go away … even when he wasn’t invited back.

Kevin Thomas — 791-6411

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Twitter: ClearTheBases