PITTSBURGH - Jason Bay and Bobby Hill have a lot in common.

Both came to the Pittsburgh Pirates late last season in trades for the club's top run-producers, Brian Giles and Aramis Ramirez.

Both have been bothered by injuries - Bay had shoulder surgery in the off-season, Hill has a lower back problem.

And both, in different ways, are among the reasons the Pirates are threatening to go above .500 in August for the first time in years.

Bay is challenging for National League Rookie of the Year honors, despite missing all of spring training and not being activated until May 7. The left fielder is hitting .311 with 13 homers and 44 RBI.

More than half of Bay's hits - 31 of 58 - have been for extra bases.

"I can't remember ever getting off to a start like this swinging the bat," Bay said. "It's not a shock to me that I'm playing well, but the numbers are a bit of a surprise.

Bay underwent right shoulder surgery Nov. 18, which knocked the 25-year-old out of winter ball and spring training.

"Missing spring training was a setback," he said. "That's when you get your timing down. When I finally got on the field, I tried to do too much at the plate and struck out a lot.

"Then I started pressing and began striking out more."

Bay struck out 59 times in his first 180 at bats this season - just under once every three at bats - but has done a lot of good in between.

He entered play this week ranked No. 2 in hitting among NL rookies, trailing Colorado's Aaron Miles by a point. He is fifth among rookies in runs scored and doubles, leads in home runs, RBI, on-base percentage (.379) and slugging percentage (.622).

Bay, Miles and Kaz Matsui of the New York Mets appear the mid-season favorites for Rookie of the Year honors.

"Jason's done a lot in a short period of time," said Pirates manager Lloyd McClendon. "He's an intelligent player. He doesn't do anything off the cuff that will cost you a ballgame."

Bay said his repaired shoulder still isn't 100 percent.

"I've learned I have to be patient with it," he said. "I had surgery there and I have to stay up on the treatments after games.

"I'm comfortable at the plate now. That's the biggest thing," he added.

After coming to Pittsburgh with pitcher Oliver Perez in the Giles trade last year, Bay hit .291 in 27 games with the Pirates, including an eight-RBI game that he matched this year.

"I was disappointed when I was traded here," he admitted. "The Padres decided to go in a different direction with older players. But the trade did give me a quicker path to the big leagues."

Hill came to Pittsburgh from Chicago in the Ramirez deal last year, but he played only one game with the Pirates before going on the shelf with a lower back injury.

The 26-year-old infielder didn't have surgery but he will need it eventually.

"I'll need it down the road," he said. "With treatments and exercise, I'm hoping it can wait until I'm through playing.

"I worked especially long and hard in the off-season to get ready for this year. I had something to prove," he added.

Hill has been proving it off the bench. He leads the league with 12 pinch-hits and is batting .335 - 12-for-34 - as a pinch-hitter this year.

Seven of Hill's 22 RBI - and both of his homers - have come in pinch-hitting roles.

"I've never done it before," he said. "It's hard. You come off the bench cold and it's usually in a situation when the team needs a hit.

"Part of it is concentration and staying focused on what you're doing. … A lot of it is luck," he added.

Hill has gotten his share of playing time this year. He has started 25 games at second base and 14 at third.

"The fact I'm not strictly a bench player has helped," he said. "I've been able to stay sharp and develop a rhythm at the plate.

"Everybody wants to play every day and I'm no exception. But our team's not gonna hit a ton of home runs and we are going to play a lot of one-run games. That one at-bat can mean a lot."