Locke, one of baseball's most unlikely All-Stars, broke camp as the club's fifth starter. But he's become much more than just an end-of-the rotation guy, someone who would have been easily replaced when Francisco Liriano and Charlie Morton got healthy, or Cole was ready for The Show.
The Pirates' rotation, however, has taken some hits throughout the year with injuries to Burnett, Wandy Rodriguez and James McDonald. The man who's been around through all that? Locke, with his 8-2 record, 2.15 ERA and, at one point, a 16-start unbeaten streak.
"This isn't something that was expected by probably anybody else except me and my teammates," said Locke, a North Conway, N.H., native and one of four active MLB players from the state. "I set my goals high. I just want to be consistent and be reliable. Just someone the team can look forward to having on the mound every fifth day."
The lefty tossed another gem Monday, allowing just three hits and two runs over seven innings, but the Pirates couldn't muster much offensively. Locke took his first loss since his first start of the season on April 7.
One thing that sticks out to Pirates manager Clint Hurdle is the 25-year-old's ability to control the inside part of the plate with his fastball. Even though Locke's heater doesn't eclipse 93 mph, he's got the confidence and trust in himself to attack the inner edge, somewhat of a lost art.
"So far, it's paid off and it's worked," said Locke, a second-round pick by the Braves in 2006. "But you have to mix it up."
Mixing it up will be critical for Locke throughout the second half of the season. After all, many of the teams he's faced were seeing him for only the first or second time. Locke locates well, another key to success, using a four-seamer, two-seamer, changeup and knuckle curve.
Of course, Locke is not perfect. Acquired from Atlanta in 2009 in a deal for Nate McLouth, he has allowed 47 walks to 73 strikeouts this year. The lefty said he's often careful with certain hitters because he'd rather allow a walk when he's behind in the count than get tagged for an extra-base hit. There's still plenty to work on.
McDonald enjoyed similar first-half success last season. Although he had already spent a few years in the big leagues, the right-hander went 9-3 with a 2.37 ERA and a .196 opponents batting average before the All-Star break last season.
After the break, McDonald had a 7.52 ERA and opponents batted .292 with a .940 OPS against him. He doesn't have much advice for Locke other than to keep doing what he's been doing.
McDonald recalled two fans bashing the Pirates on Twitter before the season for giving Locke a chance in the rotation. McDonald jumped to his teammate's defense, telling them to just wait and see.
Locke just wanted to make the team out of Spring Training, just to be in Pittsburgh, because no matter what his role was, Locke felt he could contribute. And he has, silencing some critics.
"It shows [that with] a little confidence in a guy, if you believe in him, they take off to the next level," McDonald said. "[The coaches] believed in Locke, and I think that's sparked a confidence in himself."
Locke isn't complacent, though. The lefty said he'll continue to pitch like a fifth starter in the sense that he knows he can be replaced at any time if things go south.
But Locke's expectations of himself have increased. He's had the confidence and skill set to succeed, but getting a taste of that turns goals into demands. He's allowed two runs or fewer in 13 of 18 starts this year, and he has given up no more than three runs in a start since April 18, when he allowed four.
"I never dreamed of going seven shutout innings until it happened this year. But now it's expected from myself," Locke said. "Once I can do it one time, I know I can do it again. The next goal is to go out there and throw eight, then nine [scoreless innings]."
Hurdle has always seen this conviction and confidence from the lefty, but is nonetheless proud of the way Locke has taken every lesson --- every jam, hung breaking ball, fortunate bounce, win, loss or no-decision -- and used it to get better.
"I do think he's had more of an earning mentality," Hurdle said. "He's felt he's got the skills. He's been a very confident guy for me, under the radar. He's backed that up with performance."
Where does all this confidence -- from a guy with 51 Major League innings under his belt before this season -- come from? Catcher Russell Martin saw it from Day 1 of Spring Training.
Martin pointed to Locke when explaining how simple or challenging it can be to call a game for a pitcher who doesn't have much experience. If a young pitcher hasn't figured himself out yet, it's difficult for a catcher.
"Locke has a great feel for what he wants to do out there," Martin said. "We had some good talks in Spring Training on what he likes to do. I got confidence in what he wanted to do because he had an idea of what he wanted to do."
Martin has helped Locke and the rest of the Pirates' staff become one of baseball's best. The club leads the Majors in ERA (3.09), opponents' batting average (.225) and opponents' OPS (.644).
Locke is far from the lone surprise, though. Liriano, closer Jason Grilli, setup man Mark Melancon, Justin Wilson and Jeanmar Gomez, among others, have exceeded expectations.
But it's hard to argue against Locke as the club's biggest shock. He's an All-Star in his first full season. And although he may not get to pitch at Citi Field on Tuesday because he's scheduled to start Sunday against the Mets at PNC Park, being honored is enough for him.
"I'd like to go and play catch with some of those guys," Locke said. "That's about it."