San Francisco Giants prospect Eric Surkamp has the Class AA Eastern League hitters all mixed up with his four-pitch arsenal.

Surkamp, a 23-year-old left-hander for the Richmond Flying Squirrels, has a curveball, change-up and slider that make his 87-90 mph fastball look faster. Heading into Thursday night’s start in Portland, Maine, he leads the league with a 1.92 ERA and is tied for third with 74 strikeouts while walking 22 in 65 2/3 innings.

A sixth-round pick in 2008 out of North Carolina State, Surkamp was all set to make the move to Class AA last July until he partially dislocated a hip while fielding a groundball. After surgery, he has come back as strong as he was when he struck out 108 in 101 innings at high-Class A San Jose last year.

“My hip’s been feeling good,” Surkamp said. “I missed most of the last month and a half, two months, but then I was in Arizona all offseason rehabbing. I was pretty much ready to go by spring training just like any other player.”

Perhaps the only pitcher more dominant than Surkamp in the Eastern League has been Washington Nationals prospect Brad Peacock, a right-hander who is 7-1 with a 2.28 ERA and a 91-to-15 strikeout-to-walk ratio in 67 innings for Harrisburg.

The 6-foot-4 Surkamp grew up in Cincinnati, but most of his offseason was spent at the Giants’ spring training facility. At least the parent club provided a little entertainment by winning its first World Series since moving to San Francisco after the 1957 season.

“Last year it was obviously awesome watching on TV,” Surkamp said. ”It’s cool knowing some of the guys who are up there. It gives you something to shoot for.”

Surkamp is improving his chances of cracking one of the National League’s best pitching staffs by improving his secondary pitches.

“I started working on a slider my sophomore year in college, but I didn’t really throw it much,” Surkamp said. “I threw a change-up, but it wasn’t really that good.”

With more confidence in all of his pitches, Surkamp has had few difficult outings like his last one. He dropped to 3-3 on June 3 when he allowed five runs in 4 2/3 innings in a loss to Reading. Even that was a helpful learning experience, he said Wednesday in a telephone interview.

“I wasn’t really throwing my fastball well to my glove side inside to right-handed hitters, and they had a lot of right-handed hitters,” Surkamp said. “Since then I’ve been working hard to try to fix a couple of things.”