PORTLAND, Maine — Anthony Ranaudo will be the first to tell you he is a work in progress.

The 6-foot-7, 231-pound righthander for the Portland Sea Dogs is in just his second professional season after being drafted in the first round (39th overall) by the Boston Red Sox in 2010.

He picked up his first win for the Sea Dogs in the Double-A Eastern League on Saturday as he allowed seven hits and three runs over five innings in a 5-3 win over Altoona.

He struck out four and walked one.

He had allowed three runs and just two hits in six innings in his previous start against New Britain. He walked five and struck out four and didn’t get a decision in the Sea Dogs’ 4-3 win.

Ranaudo surrendered a three-run homer to Evan Bigley in the first inning before settling down to pitch five scoreless innings.

“I’ve been throwing OK but it could be better,” said Ranaudo. “It’s still early in my season. I’m still getting repetitions.”

Ranaudo was slowed by injury earlier this spring but is healthy now.

He was ranked the Red Sox’s top pitching prospect and No. 5 overall prospect by MLB.com entering the season.

He was 9-6 with a 3.97 earned run average between Greenville of the South Atlantic League and Salem of the Carolina League in Class A ball last summer. He had 117 strikeouts, which was sixth-best in the organization, and 46 walks in 127 innings. Opponents hit .244 against him.

“Every time you take a step up into another league, the hitters are definitely more advanced. They know the strike zone a lot better,” said Ranaudo. “So each time you take the mound, it’s a learning curve. You learn something else each time out. So you feel more positive every time you take the mound.”

Ranaudo has four pitches.

He has two- and four-seam fastballs, a curve and a changeup.

Two-seam fastballs are slower than the four-seamer but they have more movement. The two-seam fastball, thrown by a righty, tails in on a righthanded hitter.

The four-seamer has more velocity and is easier for the pitcher to control.

Soxprospects.com said Ranaudo’s fastball “sits at 91-93 miles-an-hour and tops out at 95.” He should be able to add velocity as he matures, it said. And he has “average-to-better” command of it.

“He generates downward action via strong leverage from his frame,” it said.

His curve is rated the best in the organization by Baseball America.

Soxprospects.com said his curve “has tight rotation and excellent depth through the strike zone. He has outstanding feel for his curve. It’s a future swing-and-miss pitch at the major league level.”

His changeup was rated “fringe-average.”

“He shows feel and good arm-speed but does not have full trust in it,” it said.

He will need to work it “more into sequences as he approaches the upper levels of the organization.”

“I’m working on developing more consistency with my fastball,” said Ranaudo. “I want to be able to command the [strike] zone with it. I want to be able to keep it down in the zone and go in and out more with it.

“I want to get ahead of the hitters [in the count] and attack them. I also want to refine my secondary offerings. The changeup is a tough pitch to throw but it’s a great pitch,” added Ranaudo.

He is 1-1 with a 6.86 ERA in four starts in 19 ⅔ innings with 14 strikeouts and 14 walks. But opponents are hitting just .232 off him.

The Belmar, N.J., native was drafted out of St. Rose High School in the 11th round by the Texas Rangers, but he decided to attend Louisiana State University where he was chosen a third-team All-American his sophomore year.

He was 12-3 with a 3.04 earned run average for the Tigers and picked up the win in the clinching game of the 2009 College World Series, an 11-4 win over Texas.

He struck out 159 in 124 ⅓ innings.

He had arm trouble his junior year and had a 7.32 ERA to go with a 5-3 record.

But he recovered and had an outstanding summer in the Cape Cod League, going 3-0 for the Brewster Whitecaps and not allowing a run over five starts and 29⅔ innings. He gave up only 10 hits and struck out 31.

He said pitching for LSU and for two summers in the Cape Cod League — he pitched for Yarmouth-Dennis in 2009 — were “great experiences.”

“I had a lot of fun at LSU. It was a great atmosphere, a great league [Southeastern Conference] and I made some great friends,” said Ranaudo.

He said he loved the weather in the Cape Cod League and enjoyed pitching in a league where the hitters used wooden bats.

Charlie Eshbach, president of the Sea Dogs, said Ranaudo “throws hard” and he has a “smooth” delivery.

“The organization is very high on him. You don’t get to be a number one draft pick if they aren’t,” Eshbach added.